CN104066253B - Use dimming control system and the method for TRIAC dimmer - Google Patents

Abstract

Provide a kind of dimming control system using TRIAC dimmer and method.This dimming control system includes: one or more signal processing components, it is configured to receive the first signal being associated with TRIAC dimmer, the secondary signal of digit pulse type is generated according to the first signal, and secondary signal is sent to switch, control the output electric current to light-emitting component to control the Guan Bi of switch or to disconnect.

Description

Dimming control system and method using TRIAC dimmer

Technical Field

The present invention relates to integrated circuits, and more particularly to dimming control systems and methods using a TRIAC dimmer.

Background

Lighting systems incorporating Light Emitting Diodes (LEDs) often use conventional lamp dimmers (e.g., wall mounted) including TRIACs (triodes for Alternating Current) to adjust the brightness of the LEDs. A TRIAC is bidirectional and current may flow through the TRIAC in either direction (e.g., into or out of the TRIAC). A TRIAC may be triggered by a gate current (e.g., flowing in either direction), which is typically generated by applying a voltage (e.g., a positive or negative voltage) to the gate of the TRIAC. Once triggered, the TRIAC continues to conduct current until the current drops below a certain threshold (e.g., a holding current).

Fig. 1 is a simplified diagram illustrating a conventional LED lighting system using a TRIAC dimmer. For example, the lighting system 100 implements a primary side regulation scheme and a flyback structure with a single stage of Power Factor Correction (PFC) for driving one or more LEDs 172. The system 100 includes a controller 102, an AC supply component 122, a TRIAC dimmer 118, a full wave rectifier bridge 124, capacitors 126, 136, 140, 150, and 170, resistors 128, 130, 134, 138, 146, 148, 154, and 156, power switches 132 and 152, diodes 142, 144, and 168, and a transformer including a primary winding 162, a secondary winding 164, and an auxiliary winding 166. Controller 102 includes terminals 104, 106, 108, 110, 112, 114, 116, and 120. The power switches 132 and 152 are transistors, for example. In another example, the TRIAC dimmer 118 is a dimmer comprising a triode for alternating current (TRIAC).

As shown in fig. 1, the TRIAC dimmer 118 processes an AC input signal 121 from an AC supply component 122 and generates a voltage signal 123 that is processed by a full-wave rectifier bridge 124 to generate a voltage signal 174 (e.g., V |)_bulk). The TRIAC dimmer 118 is associated with a dimming cycle that includes an on period and an off period. During the on-period of the TRIAC dimmer 118, the magnitude of the voltage signal 174 is approximately equal to the AC input signal 121. During the off period of the TRIAC dimmer 118, the voltage signal 174 has a low magnitude (e.g., approximately zero). Capacitor 150 (e.g., C)₁) In response to a voltage signal 174 (e.g., V)_bulk) Through resistor 138 (e.g., R)₃) Is charged and generates a voltage signal 176 at terminal 112 (e.g., terminal VCC). If the voltage signal 176 exceeds an under-voltage-lock-out threshold voltage, the controller 102 is activated and outputs a modulation signal 178 (e.g., a Pulse Width Modulation (PWM) signal) through a terminal 116 (e.g., a terminal GATE) to close (e.g., turn on) or open (e.g., turn off) a switch 152 (e.g., M2) for normal operation of the system 100. Including resistor 130 (e.g., R)₂) And a resistor 134 (e.g., R)₄) Based on at least a voltage signal 174 (e.g., V)_bulk) A voltage signal 179 is generated. Controller 102 detects terminal 106 (e.g., terminal V)_s) Signal 179 to affect the power factor and determine the state of the TRIAC dimmer.

When the controller 102 changes the modulation signal 178 to close (e.g., turn on) the switch 152 (e.g., turn on)E.g., M2), a primary current 180 flows through the primary winding 162 and through the resistor 154 (e.g., R_s) A current sense signal 188 is generated. The controller 102 detects the current sense signal 188 at the terminal 120 (e.g., terminal CS). For example, the peak of the current sense signal 188 affects the signal 178 to open (e.g., turn off) the switch 152 in each cycle. An auxiliary current 182 flows through the auxiliary winding 166 to couple the capacitor 150 (e.g., C)₁) Charges and generates a voltage signal 184 at the auxiliary winding 166. Including resistor 146 (e.g., R)₅) And a resistor 148 (e.g., R)₆) Generates a voltage signal 186 based at least on the voltage signal 184. The controller 102 receives a signal 186 at a terminal 114 (e.g., terminal ZCD) to detect the end of a demagnetization process associated with a transformer including the secondary winding 164. In addition, the capacitor 170 is used to maintain an output voltage to output a stable current to the LED 172. During the on period of the TRIAC dimmer 118, the power switch 132 (e.g., M1) is turned off (e.g., turned off). During the off period of the TRIAC dimmer 118, the power switch 132 is closed (e.g., turned on) to provide a maintaining current (charging current) to cause the TRIAC dimmer 118 to operate normally.

Fig. 2 is a simplified conventional diagram of the controller 102 shown in fig. 1. The controller 102 includes a comparator 202, an error amplifier including a comparator 204 and a switch 205, a logic control component 206, a gate drive component 208, a signal generator 210 (e.g., a PWM signal generator), a multiplier 212, and a constant current adjustment component 214 including an error amplifier and a current detection unit. For example, the PWM signal generator is configured to generate one or more pulse width modulated signals. In another example, the PWM signal generator includes a comparator.

As shown in fig. 1 and 2, the comparator 204 receives the signal 179 and the threshold signal 226 to detect the state of the TRIAC dimmer 118 and outputs a dimming signal 228. The switch 205 is closed or opened in response to the dimming signal 228 to affect the output current to adjust the brightness of the LED172 (e.g., linearly adjust the brightness of the LED172 as a function of the output current). The constant current regulation component 214 receives the current sense signal 188 at the terminal 120 (e.g., terminal CS) to detect a peak value of the primary current 180 and integrates the peak value of the primary current 180 during a demagnetization period associated with the transformer (including the primary winding 162 and the secondary winding 164). Multiplier 212 receives processed signal 216 from constant current adjustment component 214 and voltage signal 179 from terminal 106 (e.g., terminal VS) and generates output signal 218.

The signal generator 210 receives the current sense signal 188 and the output signal 218 and generates a signal 220. During the operational period, if the modulation signal 178 is a logic high level and the switch 152 is closed (e.g., turned on), the magnitude of the primary current 180 flowing through the switch 152 increases. In response, the magnitude of the current sense signal 188 increases. If the magnitude of signal 188 becomes greater than output signal 218, signal generator 210 changes signal 220 and controller 102 changes signal 178 from a logic high level to a logic low level to open (e.g., turn off) switch 152. When the switch 152 is opened (e.g., turned off), the transformer including the primary winding 162 and the secondary winding 164 begins the demagnetization process.

The comparator 202 receives the signal 186 and the threshold signal 222 to detect whether the demagnetization process is complete. If it is determined that the demagnetization process is complete, the comparator 202 outputs a signal 224 to change the signal 178 to a logic high level. During the off period of the TRIAC dimmer 118, the logic control component 206 outputs the signal 230 to close (e.g., turn on) the switch 132 (e.g., M1) to provide a holding current for normal operation of the TRIAC dimmer 118.

As can be seen from the above description and fig. 1 and 2, the basic principle of dimming control of the conventional LED lighting system using the TRIAC dimmer is as follows: the TRIAC dimmer 118 performs switching regulation of the AC input signal 121 from the AC supply assembly 122 over a range of angles such that the voltage signal 174 (V;) is_bulk) Is equal to the AC input signal 121 during the on-period of the TRIAC dimmer 118 and is at a 0 level during the off-period of the TRIAC dimmer 118. Controller 102 detects the state of TRIAC dimmer 118 via voltage signal 179 from terminal 106 and generates a corresponding dimming signal 228 based on voltage signal 179 to match the inclusion ratioThe error amplifier of the comparator 204 and the switch 205 are controlled to adjust the output current of the illumination system 100, thereby adjusting the brightness of the LED. In addition, to maintain the TRIAC dimmer 118 to operate normally in the off state and prevent LED flicker due to abnormal operation of the TRIAC dimmer 118, the controller 102 also generates a control signal to be output by the terminal 104 (e.g., terminal TRIAC) for controlling the opening and closing of the power switch 132 to provide a maintenance current for normal operation of the TRIAC dimmer 118.

Specifically, the output average current (i.e., the current output to the LEDs 172) of the lighting system 100 shown in fig. 1 is:

$\stackrel{\‾}{I_o}=\frac{\mathrm{\φ}}{\mathrm{\π}}\×\frac{1}{2}\×N\×\frac{V_{\mathrm{ref}\_\mathrm{ea}}}{R_s}$ (equation 1)

Wherein,representing the dimming phase angle of the TRIAC dimmer 118, N represents the turns ratio of the primary winding 162 and the secondary winding 164 of the transformer U1, V_{ref_ea}Representing the reference voltage used by the constant current regulation component 214 in processing the current sense signal 188.

The illumination system 100 has some disadvantages. For example, the user may perceive the flickering of the LED172 when the dimming phase angle of the TRIAC dimmer 118 is low (e.g., the conduction time of the TRIAC dimmer 118 is less than 20% of the operating period of the TRIAC dimmer 118) or when the AC input voltage is high.

Therefore, it becomes very important to improve the dimming control technology.

Disclosure of Invention

In view of the above-described problems, the present invention provides a dimming control system and method using a TRIAC dimmer. Merely by way of example, the invention has been applied to a system for driving Light Emitting Diodes (LEDs). It will be appreciated that the invention has a broader range of applicability.

A dimming control system using a TRIAC dimmer according to an embodiment of the present invention includes: one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, generate a second signal in the form of a digital pulse from the first signal, and send the second signal to the switch to control the closing or opening of the switch to control the current output to the light emitting element.

A dimming control system using a TRIAC dimmer according to another embodiment of the present invention includes: one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, generate a third signal in the form of a digital pulse based on the first signal, and adjust a raw reference voltage of a dimming control system based on the third signal to control a current output to a light emitting element.

A dimming control method using a TRIAC dimmer according to one embodiment of the present invention includes: receiving a first signal associated with a TRIAC dimmer; generating a second signal of a digital pulse type from the first signal; a second signal is sent to the switch to control the switch to be closed or opened to control the current output to the light emitting element.

A dimming control method using a TRIAC dimmer according to another embodiment of the present invention includes: receiving a first signal associated with a TRIAC dimmer; generating a third signal of a digital pulse type from the first signal; and adjusting the original reference voltage of the dimming control system according to the third signal to control the current output to the light-emitting element.

Depending on the embodiment, one or more benefits may be obtained. These benefits, as well as various additional objects, features, and advantages of the present invention, will be more fully understood with reference to the following detailed description and accompanying drawings.

Drawings

Fig. 1 is a simplified diagram illustrating a conventional LED lighting system using a TRIAC dimmer.

Fig. 2 is a simplified conventional diagram of the controller shown in fig. 1.

Fig. 3 illustrates a controller 102-1 for the lighting system 100 shown in fig. 1, according to an embodiment of the present invention.

FIG. 4 illustrates a voltage signal 174 (e.g., V)_bulk) Compared to the actual waveform.

Fig. 5 shows a schematic diagram of a method for obtaining a stable output current implemented by the digital signal processing component 301.

Fig. 6 shows a flow chart of a method implemented by the digital signal processing component 301 for obtaining a stable output current.

Fig. 7 illustrates a dimming phase angle of the TRIAC dimmer 118 in the conventional TRIAC dimming scheme shown in fig. 1 and 2The current output to the LED.

Fig. 8 illustrates a controller 102-2 that includes both a digital signal processing component 301 and a reference voltage modulation module 801 in accordance with an embodiment of the present invention.

FIG. 9 illustrates a dimming phase angle of the controller 102-2 using the TRIAC dimmer 118 according to an embodiment of the present inventionA schematic diagram of controlling the current output to the LED 172.

FIG. 10 illustrates a dimming phase angle of the controller 102-2 using the TRIAC dimmer 118 according to an embodiment of the present inventionReference voltage V used by constant current regulation component 214 is accurately controlled_{ref_ea}Schematic diagram of (1).

FIG. 11 shows the duty cycle of the voltage control signal versus the reference voltage V_ref-eaThe corresponding relation between them.

Fig. 12 shows an exemplary circuit diagram of the reference voltage modulation component 801.

Fig. 13 shows a relationship between the luminance of the LED and the current output to the LED.

Fig. 14 illustrates a method of resolving non-uniformity in brightness variation during dimming using the dimming control system and method described above.

Detailed Description

The present invention relates to integrated circuits, and more particularly to dimming control systems and methods using TRIAC dimmers. Merely by way of example, the invention has been applied to systems for driving Light Emitting Diodes (LEDs). It will be appreciated that the invention has a broader range of applicability.

In view of the above-described drawbacks of the conventional LED lighting system using a TRIAC dimmer, the present invention provides a novel dimming control system and method using a TRIAC dimmer. For convenience, the dimming control system and method using the TRIAC dimmer according to the embodiment of the present invention will be described with continued reference to the lighting system 100 shown in fig. 1. However, it should be understood by those skilled in the art that the dimming control system and method using the TRIAC dimmer according to the embodiment of the present invention may not be applied only to the lighting system 100 shown in fig. 1, but have a wider application range.

Fig. 3 illustrates a controller 102-1 for the lighting system 100 shown in fig. 1, according to an embodiment of the present invention. It should be noted that the controller 102-1 and the part of the lighting system 100 shown in fig. 1 except the controller 102 and the LED172 constitute a dimming control system using a TRIAC dimmer according to an embodiment of the present invention. As shown in fig. 3, the controller 102-1 according to the embodiment of the present invention replaces the comparator 204 with the digital signal processing component 301 and directs the dimming signal 228-1 output by the digital signal processing component 301 to the logic control component 206 to achieve the adjustment of the output voltages of the terminal 116 (e.g., terminal GATE) and the terminal 104 (e.g., terminal TRIAC) of the controller 102-1 to achieve the flicker-free operation of the LED.

Specifically, as shown in fig. 3, the controller 102-1 according to the embodiment of the present invention includes a comparator 202, a digital signal processing component 301, a switch 205, a logic control component 206, a gate driving component 208, a signal generator 210 (e.g., a PWM signal generator), a multiplier 212, and a constant current adjusting component 214 including an error amplifier and a current detecting unit. For example, the PWM signal generator is configured to generate one or more pulse width modulated signals. In another example, the PWM signal generator includes a comparator.

As shown in fig. 1 and 3, the digital signal processing component 301 receives the voltage signal 179 at the terminal 106 (e.g., the terminal VS) to detect the state of the TRIAC dimmer 118 and outputs the dimming signal 228-1. The switch 205 is closed or opened in response to the dimming signal 228-1 to affect the output current to adjust the brightness of the LED172 (e.g., to linearly or non-linearly adjust the brightness of the LED172 as a function of the output current). The constant current regulation component 214 receives the current sense signal 188 at the terminal 120 (e.g., terminal CS) to detect a peak value of the primary current 180 and integrates the peak value of the primary current 180 during a demagnetization period associated with the transformer (including the primary winding 162 and the secondary winding 164). Multiplier 212 receives processed signal 216 from constant current adjustment component 214 and voltage signal 179 from terminal 106 (e.g., terminal VS) and generates output signal 218.

The signal generator 210 receives the current sense signal 188 and the output signal 218 and generates a signal 220. During the operational period, if the modulation signal 178 is a logic high level and the switch 152 is closed (e.g., turned on), the magnitude of the primary current 180 flowing through the switch 152 increases. In response, the magnitude of the current sense signal 188 increases. If the magnitude of the current sense signal 188 becomes greater than the output signal 218, the signal generator 210 changes the signal 220 and the controller 102 changes the signal 178 from a logic high level to a logic low level to open (e.g., turn off) the switch 152. When the switch 152 is opened (e.g., turned off), the transformer including the primary winding 162 and the secondary winding 164 begins the demagnetization process.

The comparator 202 receives the signal 186 and the threshold signal 222 to detect whether the demagnetization process is complete. If it is determined that the demagnetization process is complete, the comparator 202 outputs a signal 224 to change the signal 178 to a logic high level. During the off period of the TRIAC dimmer 118, the logic control component 206 outputs the signal 230 to close (e.g., turn on) the switch 132 (e.g., M1) to provide a holding current for normal operation of the TRIAC dimmer 118.

Further, in the controller 102-1 shown in fig. 3, the digital signal processing component 301 performs analog/digital conversion on the voltage signal 179 received at the terminal 106 (e.g., the terminal VS), generates a digital pulse signal corresponding to the phase angle of the voltage signal 179, and then generates the dimming signal 228-1 of a digital pulse type according to the digital pulse signal. The dimming signal 228-1 is directed to the switch 205 and the logic control component 206. The switch 205 is closed or opened in response to the dimming signal 228-1 to generate a stable output current to adjust the brightness of the LED 172. The logic control component 206 generates a signal 230 to control the closing (e.g., turning on) and opening (e.g., turning off) of the switch 132 (e.g., M1) and correspondingly controls the gate drive component 208 to generate the modulation signal 178 at a logic high level or a logic low level based on the signal 224 received from the comparator 202, the signal 220 received from the signal generator 210, and the dimming signal 228-1 received from the digital signal processing component 301.

Since the voltage signal 179 is caused by the inclusion of the resistor 130 (e.g., R)₂) And a resistor 134 (e.g., R)₄) Based on at least a voltage signal 174 (e.g., V)_bulk) The voltage signal 179 is generated so that it has the same periodic characteristics as the voltage signal 174. In addition, due to voltage signal 174 (e.g., V)_bulk) Is generated by processing the AC input signal 121 from the AC supply component 122 by the TRIAC dimmer 118, the phase angle of the voltage signal 174 is consistent with the dimming phase angle of the TRIAC dimmer 118. The effect of the phase angle of the voltage signal 179 on the brightness of the LEDs 172 (i.e., the effect of the phase angle of the voltage signal 174 on the brightness of the LEDs 172) will now be described.

FIG. 4 illustrates a voltage signal 174 (e.g., V)_bulk) Compared to the actual waveform. In FIG. 4, V_bulk1Represents the ideal waveform, V, of the voltage signal 174_bulk2Representing the actual waveform, V, of the voltage signal 174_acRepresents the waveform, V, of the AC input signal 121 from the AC supply assembly 122_TRIACRepresenting the waveform of the voltage signal 123 generated by the TRIAC dimmer 118 by processing the AC input signal 121.

Theoretically, during the on-period of the TRIAC dimmer 118, the voltage signal 174 (e.g., V)_bulk) Is identical in voltage waveform (V)_bulk1An ideal waveform of the voltage signal 174 is shown). However, in practical applications, due to the characteristics of the TRIAC dimmer 118, the positive and negative levels of the AC input signal 121 may differ to some extent, which may cause the actual waveforms of the voltage signal 174 generated after the AC input signal 121 is rectified by the full-wave rectifier bridge 124 to differ to some extent in different periods (V |)_bulk2Showing the actual waveform of the voltage signal 174). Such a V_bulk2The difference in voltage waveforms will eventually result in a large difference in the current output to the LED172, thereby creating a phenomenon of LED flicker that the human eye can perceive. Since the brightness of the LED172 is mainly determined by the current output to the LED,a large periodic difference in the current output to the LED may be caused when the conduction angle (i.e., the dimming phase angle) of the TRIAC dimmer 118 is large, so that the human eye may perceive the LED to flicker. That is, the waveform unevenness or the large-and-small-wave phenomenon of the voltage signal 174 due to the characteristics of the TRIAC dimmer 118 is a factor causing the current output to the LED to be unstable, and eventually causing the LED to flicker.

The controller 102-1 for the lighting system 100 shown in fig. 1 according to an embodiment of the present invention is proposed in view of the reason for LED flicker generation as analyzed in connection with fig. 4. As shown in fig. 3, in one embodiment, the approximately uniform voltage signal provided to terminal 116 (e.g., terminal GATE) and terminal 104 (e.g., terminal TRIAC) of controller 102 is generated by directing digital pulse-type dimming signal 228-1 generated by digital signal processing component 301 from voltage signal 179 to logic control component 206, thereby providing a steady current to LED 172.

In particular, fig. 5 shows a schematic diagram of a method implemented by the digital signal processing component 301 for obtaining a stable output current (i.e., the current output to the LED 172). In FIG. 5, V_bulkPhase represents the waveform of the digital pulse signal corresponding to the Phase angle of the voltage signal 179 generated by the digital signal processing unit 301 from the voltage signal 179 (which also reflects the actual waveform of the voltage signal 179), DIM represents the waveform of the digital pulse-type dimming signal 228-1 generated by the digital signal processing unit 301 modulating the digital pulse signal Phase from the voltage signal 179, and TRIAC represents the waveform of the signal 230 generated by the logic control unit 206 from the signal 224, the signal 220, and the signal 228-1 to be output from the terminal 104 (e.g., terminal TRIAC) of the controller 102-1. Note that voltage signal 179 is generated by including resistor 130 (e.g., R)₂) And a resistor 134 (e.g., R)₄) Based on at least a voltage signal 174 (e.g., V)_bulk) The resulting, and therefore voltage signal 179 has the same waveform as the voltage signal 174.

Fig. 6 shows a flow chart of a method implemented by the digital signal processing component 301 for obtaining a stable output current. The specific processing of the digital signal processing module 301 will be described below with reference to fig. 5 and 6. As shown in fig. 6, the digital signal processing component 301 in the controller 102-1 performs the following processing: performing analog/digital conversion on the voltage signal 179 input from the terminal 106 (for example, the terminal VS), generating a digital pulse signal Phase corresponding to the Phase angle of the voltage signal 179 and recording the Phase angle Φ n of each cycle of the voltage signal 179 (i.e., performing step S602); comparing the phase angles (e.g., φ n-3, φ n-2, φ n-1, φ n) of 4 consecutive cycles of the voltage signal 179 and selecting the smallest phase angle φ n _ min (i.e., performing step S604); comparing the selected minimum phase angle φ n _ min with the phase angle φ n +1 of the next cycle after the consecutive 4 cycles (i.e., performing step S606); if φ n +1 is greater than φ n _ min, then the digital pulse signal Phase is modulated with information indicative of φ n _ min to generate a dimming signal 228-1 indicative of φ n _ min (i.e., only a portion of the Phase angle of φ n _ min in a cycle of the voltage signal 179 is used for dimming control, while the remainder of the cycle is not involved in dimming control) (i.e., step S608-1 is performed); if φ n +1 is smaller than φ n _ min, the digital pulse signal Phase is modulated with information indicative of φ n +1 to generate a dimming signal 228-1 indicative of φ n +1 (the n +1 th cycle of the voltage signal 179 is used for dimming control in its entirety) (i.e., step S608-2 is performed).

In one embodiment, the dsp 301 may utilize a first-in-first-out (FIFO) queue with a length of 4 to complete the above steps S602 to S608-1/2 (i.e., execute step S610) until the controller is shut down. Specifically, for the voltage signal 179, the digital signal processing component 301 performs a phase angle magnitude comparison every 4 consecutive cycles and generates φ n _ min, and after the next 5 th cycle enters the FIFO while the previous 1 st cycle leaves the FIFO, performs a judgment process on the new 4 consecutive cycles consisting of the incoming 5 th cycle and the previous 2-4 th cycles, which is continuously performed with the increase of time (cycle) until the shutdown of the system is finished. It should be noted that, comparing the phase angle magnitudes of 4 consecutive cycles is only illustrative, and in a specific application, the phase angles of 2, 3, 5, or more consecutive cycles may be compared according to actual needs for subsequent processing.

That is, in the method for obtaining a stable output current implemented by the digital signal processing component 301 described in connection with fig. 5 and 6, the dimming signal 228-1 with very small difference between phase angles of different cycles is generated by finding the smallest phase angle in a plurality of consecutive cycles of the voltage signal 179 in sequence, thereby obtaining a substantially stable current output to the LED. This is because, in the case where the difference between the phase angles of different periods of the dimming signal 228-1 is very small, the difference between the currents output to the LEDs will become very small, so that the LEDs do not generate a flicker phenomenon that can be perceived by human eyes.

When the conventional TRIAC dimming scheme shown in fig. 1 and 2 is adopted, since the current output to the LED172 satisfies equation 1, when the dimming phase angle of the TRIAC dimmer 118Sufficiently small, due to the voltage signal 174 (e.g., V) generated by rectifying the voltage signal 123 generated by the TRIAC dimmer 118 processing the AC input signal 121_bulk) Too low a voltage will cause the lighting system 100 shown in fig. 1 and 2 to fail to maintain normal constant current control of the LEDs 172, such that the minimum magnitude of the current output to the LEDs 172 is limited. As shown in fig. 7, at the dimming phase angle of the TRIAC dimmer 118Is less thanAfter 0, the current output to the LED changes rapidly, resulting in low dimming resolution of the lighting system 100.

To achieve high resolution adjustment of the brightness of the LEDs 172, embodiments in accordance with the inventionThe dimming control system using the TRIAC dimmer may further include a reference voltage modulation module 801 in the controller 102-1. Fig. 8 illustrates a controller 102-2 that includes both a digital signal processing component 301 and a reference voltage modulation module 801 in accordance with an embodiment of the present invention. In the controller 102-2 shown in fig. 8, the dimming phase angle at the TRIAC dimmer 118 will beSmall enough to still maintain a steady current output to the LED172Before 0, according to the dimming phase angle of the TRIAC dimmer 118The current output to the LED172 is adjusted to be low enough to achieve high resolution dimming control (the principle is shown in fig. 9).

From equation 1 above, the reference voltage V input to the error amplifier used by the constant current adjustment component 214 in processing the current sense signal 188_{ref_ea}The current output to the LED172 can be affected. Thus, the controller 102-2 according to an embodiment of the present invention will pass the dimming phase angle according to the TRIAC dimmer 118Regulating V_{ref_ea}To achieve high resolution dimming control. As shown in fig. 8, the reference voltage modulation component 801 is connected between the digital signal processing component 301 and the constant current adjusting component 214. Specifically, the reference voltage modulation component 801 receives a control signal 802 (e.g., Ctrl) from the digital signal processing component 301, and generates a reference voltage V input to the error amplifier in the constant current adjustment component 214 according to the control signal 802_{ref_ea}。

FIG. 10 illustrates a dimming phase angle of controller 102-2 using TRIAC dimmer 118Accurately controlling the reference voltage V input to the error amplifier in the constant current regulation component 214_{ref_ea}Schematic diagram of (1). As shown in FIG. 10, V_ref0Is the reference voltage input to the error amplifier in the constant current adjustment component 214 when the dimming phase angle phi of the TRIAC dimmer 118 is at its maximum (hereinafter also referred to as the original reference voltage, which is predetermined for a fixed dimming system); as phi decreases, V_{ref -ea}And correspondingly decreases to 0 before decreasing to the minimum angle phi 0 required to maintain a steady current output to the LED 172. Since the current output to the LED can keep the LED operating normally without flickering when the dimming phase angle phi of the TRIAC dimmer is at a higher level, this stage may also be performed without dimming V_{ref_ea}And (6) carrying out adjustment.

Specifically, in the controller 102-2 shown in fig. 8, the digital signal processing component 301 employs a Pulse Width Modulation (PWM) method (i.e., by digital signal duty cycle) to precisely control V_{ref_ea}The size of (2). That is, the digital signal processing component 301 outputs a high frequency digital signal (e.g., Ctrl in fig. 8, i.e., the above-mentioned control signal 802) with a duty cycle (duty) according to the magnitude of the dimming phase angle Φ of the TRAIC dimmer detected by the voltage signal 179; the reference voltage modulation component 801 is based on the control signal 802 from the digital signal processing component 301 and the original reference voltage V_ref0Generating a reference voltage V to be inputted to an error amplifier in the constant current adjusting block 214_{ref_ea}. Thus, the duty ratio of the control signal 802 and the reference voltage V input to the error amplifier in the constant current adjusting component 214 can be realized_ref-eaAnd (4) corresponding to the size. FIG. 11 shows the duty cycle of the control signal 802 versus the reference voltage V_ref-eaThe corresponding relation between them. As shown in fig. 11, the duty cycle of the control signal 802 (e.g., Ctrl) fully characterizes the magnitude of the dimming phase angle Φ of the TRIAC dimmer 118.

Fig. 12 shows an exemplary circuit diagram of the reference voltage modulation component 801. As shown in FIG. 12, the reference voltage modulation component 801 includes an operational amplifier OP1,An analog one-out-of-two switch K1 and a capacitor C1, wherein the predetermined voltage V_ref0The buffer connected with the operational amplifier OP1 is output to one end of an analog alternative switch K1, the other input end of K1 is grounded, the output end of K1 is connected with a capacitor C1, and the voltage of the capacitor C1 is V_{ref_ea}(the voltage of the capacitor C1 is directed to the input of the error amplifier in the constant current control component 214), the control signal of K1 is the voltage control signal 802 (e.g., Ctrl) from the digital signal processing component 301. The digital pulse type voltage control signal 802 controls the gating of the input signal of the analog one-out-of-two switch K1. Specifically, when Ctrl is logic 1, K1 gates the OP1 output, i.e., V_ref0(ii) a When Ctrl is logic 0, K1 is gated, i.e., 0V. After filtering by the capacitor C1, the average voltage Vref _ ea of C1 can be expressed by equation 2.

V_{ref_ea}＝Duty×V_ref0(equation 2)

Although the luminance of the LED is mainly determined by the current output to the LED, the current output to the LED and the luminance of the LED are not linearly related to each other. As shown in fig. 13, the relationship between the luminance of the LED and the current output to the LED is that the luminance of the LED changes quickly when the current output to the LED is small, and changes slowly when the current output to the LED is large. Therefore, in dimming using the dimming control system and method using the TRIAC dimmer described above in conjunction with fig. 1, 3, and 8, there occurs a problem in that the brightness of the LEDs is not uniformly changed. Fig. 14 illustrates a method of resolving non-uniformity in brightness variation during dimming using the dimming control system and method described above. In particular, the digital signal processing component 301 may generate the control signal 802 (e.g., Ctrl) based on the dimming phase angle Φ of the TRIAC dimmer 118 by causing a non-linear relationship between the dimming phase angle Φ and the control signal 802, and thus the dimming phase angle Φ and the reference voltage V_ref-eaTo make V have a non-linear relationship_ref-eaOr the current output to the LED, appears non-linear to compensate for the non-linear relationship between LED current and brightness, which is the effect of the dashed line in fig. 14.

The other processes of the digital processing component 301 in the controller 102-2, and the other components other than the reference voltage modulating component 801 are the same as described above with reference to fig. 1 and 3. Therefore, in order not to unnecessarily obscure the present invention, a detailed description thereof will not be provided herein. In addition, it will be appreciated by those skilled in the art that the above-described high resolution adjustment process of the current output to the LED172 may also be performed independently of the process of achieving flicker-free operation of the LED172, without affecting the operation of other components in the controller.

Some or all of the components of the various embodiments of the present invention, alone and/or in combination with at least one other component, are implemented using one or more software components, one or more hardware components, and/or one or more combinations of software and hardware components. In another example, some or all of the components in various embodiments of the present invention are implemented in one or more circuits, for example, in one or more analog circuits and/or one or more digital circuits, alone and/or in combination with at least one other component. In yet another example, various embodiments and/or examples of the invention may be combined.

While specific embodiments of the invention have been described, it will be apparent to those skilled in the art that other embodiments exist that are equivalent to the described embodiments. It is understood, therefore, that this invention is not limited to the particular embodiments shown, but is only limited by the scope of the appended claims.

Claims (10)

1. A dimming control system using a TRIAC dimmer, comprising:

one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, generate a second signal in the form of a digital pulse from the first signal, and send the second signal to a switch to control the switch to be closed or opened to control current output to a light emitting element, wherein

The one or more signal processing components generate the second signal by:

performing analog/digital conversion on the first signal to generate a digital pulse-type fourth signal corresponding to a phase angle of the first signal;

finding out the minimum phase angle of the first signal in each unit by taking two or more continuous periods of the first signal as a unit;

modulating the fourth signal with the found minimum phase angle in each unit, generating the second signal.

2. The dimming control system of claim 1, wherein the one or more signal processing components are further configured to:

and generating a digital pulse type third signal according to the first signal, and adjusting an original reference voltage of the dimming control system according to the third signal so as to control the current output to the light-emitting element.

3. The dimming control system of claim 2, wherein the one or more signal processing components are further configured to:

generating the third signal with a preset relation between the duty ratio and the phase angle of the first signal according to the phase angle information of the first signal;

and adjusting the original reference voltage of the dimming control system according to the duty ratio information of the third signal.

4. A dimming control system as claimed in claim 3, wherein there is a non-linear relationship between the duty cycle of the third signal and the phase angle of the first signal.

5. The dimming control system of claim 2, wherein the one or more signal processing components comprise a digital signal processing component, wherein the process of generating the second and third signals is performed by the digital signal processing component.

6. The dimming control system of claim 5, wherein the one or more signal processing components comprise a reference voltage modulation component, wherein the process of adjusting the raw reference voltage of the dimming control system according to duty cycle information associated with the third signal is performed by the reference voltage modulation component.

7. A dimming control method using a TRIAC dimmer, comprising:

receiving a first signal associated with a TRIAC dimmer;

generating a second signal of a digital pulse type from the first signal;

sending the second signal to a switch to control the switch to be closed or opened to control the current output to the light emitting element,

wherein the processing to generate the second signal comprises:

performing analog/digital conversion on the first signal to generate a digital pulse-type fourth signal corresponding to a phase angle of the first signal;

finding out the minimum phase angle of the first signal in each unit by taking two or more continuous periods of the first signal as a unit;

modulating the fourth signal with the found minimum phase angle in each unit, generating the second signal.

8. The dimming control method of claim 7, further comprising:

generating a third signal of a digital pulse type from the first signal;

and adjusting the original reference voltage of a dimming control system according to the third signal so as to control the current output to the light-emitting element.

9. The dimming control method according to claim 8,

generating the third signal having a predetermined relationship between duty cycle and phase angle of the first signal according to phase angle information associated with the first signal; and is

Adjusting the raw reference voltage of the dimming control system according to duty cycle information associated with the third signal.

10. The dimming control method of claim 9, wherein a non-linear relationship exists between a duty cycle of the third signal and a phase angle of the first signal.