TWI459854B - A white LED (WLED) drive circuit and driving method for three - terminal controllable silicon dimmer - Google Patents

Description

White LED (WLED) driving circuit and driving method suitable for three-terminal controllable 矽 dimmer

The invention relates to a driving method and a driving circuit for an LED, in particular to a driving method and a driving circuit for a three-terminal controllable dimming device suitable for a white LED (WLED).

Nowadays, the application of WLED lighting technology has become more and more extensive, and replacing traditional bulb lighting with WLED has become a major trend in the development of WLED lighting technology. However, one of the difficulties in replacing traditional bulb illumination with WLED is that the WLED driver circuit must be compatible with the standard three-terminal controllable dimmer to achieve brightness adjustment of the WLED during illumination, which is not only the user's needs, but also Extend the life of the WLED.

Traditional three-terminal controllable dimmers are designed for purely resistive load lamps such as incandescent lamps and iodine-tungsten lamps. Since the WLED does not exhibit resistive load characteristics, the use of a conventional three-terminal controllable dimmer to dim the WLED does not achieve good results. FIG. 1 is a schematic diagram of a driving circuit for driving a WLED using a conventional three-terminal controllable dimming resistive lamp illumination driving structure in the prior art. The driving circuit 100 includes a three-terminal controllable dimmer 101, an electronic transformer 103, a rectifier 105, and a WLED driver 107 for driving the WLED 109. The three-terminal controllable dimming device 101 controls the conduction time of the internal three-terminal bidirectional controllable switch to control the energy transmitted from the AC power supply (usually 110V-220V AC) to the driving circuit 100 to output a conduction. Angle controlled high Press alternating current. The conduction time of the three-terminal bidirectional controllable switch in one power supply cycle is represented by a corresponding angle. Generally, the opening of the three-terminal bidirectional controllable switch is controlled by a control signal, and when the current in the three-terminal bidirectional controllable switch is reduced to a certain value, it is automatically turned off, so the time when the control signal arrives The on-time of the three-terminal bidirectional controllable switch is determined. The electronic transformer 103 receives the high voltage alternating current and converts it into low voltage alternating current. The rectifier 105 rectifies the low voltage alternating current and outputs low voltage direct current for powering the WLED driver 107 to drive the WLED 109 to operate. In the dimming process, generally, the high-voltage alternating current output from the three-terminal controllable dimmer 101 is not uniformly symmetrical, and the low-voltage alternating current output from the electronic transformer 103 is also asymmetric, and the low-voltage direct-current signal processed by the rectifier 105 is included. 50Hz low-frequency AC voltage ripple, if the high-voltage AC output from the three-terminal controllable dimmer 101 occurs during the dimming process, some conduction angle loss occurs, that is, in a certain power supply cycle, if the three-terminal bidirectional control is possible The control signal for the opening of the control switch is late, so that the conduction time of the three-terminal bidirectional controllable switch is shorter, that is, the conduction angle is small, so that the three-terminal bidirectional controllable switch is not fully turned on in time, then This smaller conduction angle is lost, so that the low voltage DC signal output by the rectifier 105 will also contain a lower frequency AC voltage ripple below 50 Hz. These 50 Hz or lower frequency AC voltage ripples are input to the WLED driver 107, which causes a 50 Hz or lower frequency AC current in the WLED 109 to flow, causing the WLED to flicker during the dimming process, which should be eliminated in practical applications. of.

Therefore, in order to avoid the WLED flashing during the dimming process, the detection three It is important to control the conduction angle of the dimmer and process it to adjust the brightness of the WLED.

The object of the present invention is to solve the problem that the existing three-terminal controllable dimmer is caused by the low frequency alternating current to cause the dimming process to flicker, and to provide a WLED driving method and a driving circuit suitable for the three-terminal controllable dimming device, the driving The method and the driving circuit can detect the conduction angle of the three-terminal controllable dimmer and apply it to the brightness adjustment of the WLED, thereby realizing a wide range, smooth and flicker-free WLED dimming.

Another object of the present invention is to provide an electronic transformer applied to the above dimmer to detect its conduction angle and apply to the brightness adjustment of the WLED, thereby achieving a wide range, smooth flicker-free WLED dimming.

The technical solution adopted by the invention is as follows: a WLED driving circuit suitable for a three-terminal controllable 矽 dimmer, comprising: a three-terminal controllable 矽 dimmer for coupling a high-voltage AC power supply to control the output conduction angle a high voltage alternating current; an electronic transformer for receiving the high voltage alternating current to output a pulse width modulated low voltage direct current; a WLED driver for receiving the pulse width modulated low voltage direct current to output a WLED driving signal; and the electronic transformer Detecting a conduction angle of the high-voltage alternating current, and adjusting an output of the pulse width modulated low-voltage direct current based on the conduction angle Empty ratio.

In a preferred embodiment of the present invention, the electronic transformer may include: a conduction angle detecting module, a conduction angle modulation module, and a converter module. The conduction angle detecting module is configured to detect a conduction angle of the high-voltage alternating current, and generate a first pulse width modulation signal based on the conduction angle; and the conduction angle modulation module is configured to receive the Decoding a first pulse width modulation signal, filtering it to generate a DC voltage signal reflecting a DC average value of the first pulse width modulation signal, and comparing the DC voltage signal with a triangular wave signal to output a second pulse width a modulation signal; and the converter module is controlled by the second pulse width modulation signal to convert the high voltage alternating current into the pulse width modulation low voltage direct current.

Preferably, the frequency and duty ratio of the first pulse width modulation signal are consistent with the frequency and duty ratio of the conduction angle signal; and the duty ratio of the second pulse width modulation signal is controlled by the conduction The angular signal is adjusted with a frequency higher than the frequency of the conduction angle signal.

The conduction angle detecting module can be implemented by using a plurality of conduction angle detecting circuit structures in the prior art. For example, according to an embodiment of the present invention, the conduction angle detecting module includes a rectifying circuit and a linear-like voltage regulator circuit. Wherein the rectifier circuit is configured to receive the high voltage alternating current and rectify it into high voltage direct current; and the linear regulator circuit includes at least one voltage stabilizing diode and a controllable switch, the cathode of the voltage stabilizing diode is coupled to the high voltage direct current via a first resistor, the anode is coupled to the ground, and the gate of the controllable switch is coupled to the voltage regulator a cathode of the diode, the drain of which is coupled to the high voltage direct current, the source thereof is coupled to the ground via a second resistor, and the source of the controllable switch is used as the conduction angle detecting module Output.

Additionally, in various embodiments of the present invention, a zero-crossing comparator circuit may be substituted for the linear-type regulator circuit, and the zero-crossing comparator circuit receives and processes the high-voltage direct current to output The first pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal is at a high level, and when the high voltage direct current voltage is zero, the first pulse width modulation The signal is low.

The conduction angle modulation module may include: a low pass filter for filtering the first pulse width modulation signal to output the DC voltage signal; and a pulse width modulation comparator for The DC voltage signal is compared with the triangular wave signal to output the second pulse width modulation signal.

The converter module can be any AC-DC converter that converts high voltage alternating current to low voltage direct current.

A WLED driving method suitable for a three-terminal controllable 矽 dimmer comprises: receiving a high-voltage alternating current power supply to output a high-voltage alternating current with a conduction angle controlled; converting the high-voltage alternating current into a pulse width modulated low-voltage direct current; The pulse width modulated low voltage direct current input to the WLED driver to adjust its driving WLED, wherein converting the high voltage alternating current into pulse width modulated low voltage direct current further comprises detecting a conduction angle of the high voltage alternating current, and based on the conduction angle Adjust the pulse width of the output to adjust the duty cycle of the low voltage DC.

According to a preferred embodiment of the present invention, the step of converting the high voltage alternating current into the pulse width modulated low voltage direct current comprises: detecting a conduction angle of the high voltage alternating current, and generating a first pulse width modulation signal; Decoding a first pulse width modulation signal to generate a DC voltage signal reflecting a DC average of the first pulse width modulation signal; comparing the DC voltage signal with a triangular wave signal to generate a second pulse width modulation And converting the high voltage alternating current to the pulse width modulated low voltage direct current based on the control of the second pulse width modulated signal.

Preferably, the frequency and duty ratio of the first pulse width modulation signal are consistent with the frequency and duty ratio of the conduction angle signal; and the duty ratio of the second pulse width modulation signal is controlled by the conduction The angular signal is adjusted with a frequency higher than the frequency of the conduction angle signal.

According to a preferred embodiment of the present invention, the conduction angle detecting module is configured to detect a conduction angle of the high-voltage alternating current, and the conduction angle detecting module includes a rectifying circuit and a linear-like regulator circuit, wherein the rectifying circuit Receiving the high voltage alternating current and rectifying it into high voltage direct current; The linear regulator circuit includes at least one voltage stabilizing diode and a controllable switch, and the cathode of the voltage stabilizing diode is coupled to the high voltage direct current via a first resistor, and the anode is coupled To the ground, the gate of the controllable switch is coupled to the cathode of the voltage stabilizing diode, the drain is coupled to the high voltage direct current, and the source thereof is coupled to the ground via the second resistor. The source of the controllable switch is used as an output end of the conduction angle detecting module.

Additionally, in various embodiments of the present invention, a zero-crossing comparator circuit may be substituted for the linear-type regulator circuit, and the zero-crossing comparator circuit receives and processes the high-voltage direct current to output The first pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal is at a high level, and when the high voltage direct current voltage is zero, the first pulse width modulation The signal is low.

In accordance with a preferred embodiment of the present invention, the first pulse width modulated signal is filtered using a low pass filter.

According to a preferred embodiment of the present invention, the comparator is configured to receive the DC voltage signal and the triangular wave signal through a pulse width modulation to output the second pulse width modulation signal.

In accordance with a preferred embodiment of the present invention, the high voltage alternating current is converted to the pulse width modulated low voltage direct current by an AC-DC converter to receive the high voltage alternating current and the second pulse width modulated signal.

The present invention also provides an electronic transformer that receives high voltage alternating current and outputs a pulse width modulated low voltage direct current, the electronic transformer comprising: a conduction angle detecting module for detecting a conduction angle of the high voltage alternating current; The control module adjusts the duty cycle of the low voltage direct current based on the detected conduction angle signal to adjust the output pulse width.

An electronic transformer provided by the present invention, the control module includes a conduction angle modulation module and a converter module, wherein the conduction angle detection module is based on the detected conduction angle signal to generate a first a pulse width modulation signal; the conduction angle modulation module is configured to receive the first pulse width modulation signal, and filter the same to generate a DC voltage signal reflecting a DC average value of the first pulse width modulation signal, And comparing the DC voltage signal with the triangular wave signal to output a second pulse width modulation signal; and the converter module is controlled by the second pulse width modulation signal to convert the high voltage alternating current into The pulse width modulates the low voltage direct current.

The invention provides an electronic transformer, wherein a frequency and a duty ratio of the first pulse width modulation signal are consistent with a frequency and a duty ratio of the conduction angle signal; and a duty of the second pulse width modulation signal The frequency is higher than the frequency of the conduction angle signal by being adjusted by the conduction angle signal.

An electronic transformer provided by the present invention, the conduction angle detecting module includes a rectifying circuit and a linear regulator circuit, wherein the rectifying circuit is configured to receive the high voltage alternating current and rectify it into high voltage direct current; a linear regulator circuit comprising at least one voltage stabilizing diode and a controllable switch, the cathode of the voltage stabilizing diode being coupled to the high voltage direct current via a first resistor, the anode of which is coupled to the ground The controllable switch a gate is coupled to the cathode of the voltage stabilizing diode, a drain is coupled to the high voltage direct current, and a source is coupled to the ground via a second resistor, a source of the controllable switch Used as an output of the conduction angle detecting module.

The invention provides an electronic transformer, the linear regulator circuit can also be replaced by a zero-crossing detection comparator circuit, which receives and processes the high-voltage direct current to output the first Pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal is at a high level, and when the high voltage direct current voltage is zero, the first pulse width modulation signal is low quasi.

An electronic transformer provided by the present invention, the conduction angle modulation module includes a low pass filter and a pulse width modulation comparator, wherein the low pass filter is configured to receive the first pulse width modulation signal And converting the DC voltage signal; and the pulse width modulation comparator for comparing the DC voltage signal with the triangular wave signal to output the second pulse width modulation signal.

The invention provides an electronic transformer, which is an AC-DC converter that converts high-voltage alternating current into low-voltage direct current.

The invention has the beneficial effects of the WLED driving method and the driving circuit applicable to the three-terminal controllable 矽 dimmer: the WLED driving method and the driving circuit for the three-terminal controllable 矽 dimmer provided by the invention provide a novel The electronic transformer can detect the conduction angle of the high-voltage alternating current output by the three-terminal controllable dimmer, and convert the high-voltage alternating current into a pulse width modulated low-voltage direct current whose duty ratio is adjusted by the conduction angle. Pulse width adjustment The variable low voltage direct current supplies power to the WLED driver to drive the WLED operation, and the three-terminal controllable dimmer can adjust the duty ratio of the pulse width modulated low voltage DC voltage signal to adjust the average current flowing through the WLED tube. In order to change the brightness of the WLED, the pulse width modulation low-voltage direct current does not include an AC voltage ripple having a frequency of 50 Hz or less, and therefore, the WLED driving method and driving of the present invention suitable for a three-terminal controllable 矽 dimmer The circuit and the electronic transformer used in it can achieve smooth flicker-free dimming of the WLED.

The three-terminal controllable dimming WLED driving method and driving circuit of the embodiment of the present invention are described in detail below. In the following description, some specific details, such as specific circuit structures in the embodiments and specific parameters of these circuit elements, are used to provide a better understanding of the embodiments of the invention. Those skilled in the art will appreciate that the present invention can be implemented even in the absence of many details or combinations of other methods, elements, materials, and the like.

2 is a schematic diagram of a three-terminal controllable dimming WLED driving circuit according to an embodiment of the present invention. The driving circuit 200 mainly includes a three-terminal controllable dimmer 202, an electronic transformer 204 and a WLED driver 206 for driving the WLED tube 208. The three-terminal controllable dimming device 202 is configured to receive a high-voltage AC power supply voltage U1 and generate a high-voltage alternating current U2 with a conduction angle controlled; the electronic transformer 204 detects a conduction angle of the high-voltage alternating current U2, And converting the high voltage alternating current U2 into a PWM (pulse width modulation) low voltage direct current U3 whose duty ratio is adjusted by the conduction angle; the WLED driver 206 receives the PWM low voltage direct current U3 and outputs a WLED drive A current I _{LED is used} to drive the WLED 208 to operate.

As shown in FIG. 3, a three-terminal controllable dimming WLED driving circuit 200 according to an embodiment of the present invention includes three main parts: a conduction angle detecting module, a conduction angle modulation module, and a transformation. Module. The conduction angle detecting module is coupled to the output end of the three-terminal controllable dimming device 202 for receiving the high-voltage alternating current U2 and outputting a first characteristic indicating the conduction angle of the high-voltage alternating current U2. a PWM signal Ua; the conduction angle modulation module is coupled to the output end of the conduction angle detecting module for receiving the first PWM signal Ua, and performing low-pass filtering to generate a DC voltage a signal U _dc and comparing the DC voltage signal U _dc with a triangular wave signal to output a second PWM signal Um; the converter module is coupled to the three-terminal controllable dimmer 202 The output end and the output end of the conduction angle modulation module respectively receive the high voltage alternating current U2 and the second PWM signal Um, and are controlled by the second PWM signal Um to the high voltage alternating current U2 Converted to the PWM low voltage direct current U3.

FIG. 4 is a diagram showing main signal waveforms of a three-terminal controllable dimming WLED driving circuit in a normal operation according to an embodiment of the present invention. The operation principle of the three-terminal controllable dimming WLED driving circuit 200 proposed by the present invention will be further described below in conjunction with the waveform diagram shown in FIG.

During the dimming process, the three-terminal controllable dimmer 202 receives the high-voltage AC supply voltage U1, and adjusts the on-time of the internal three-terminal bidirectional controllable switch so that the high-voltage AC supply voltage U1 is in one cycle. Energy is transferred to the drive circuit 200 only during the on-time of the triac. Generally, the opening of the three-terminal bidirectional controllable switch is controlled by a control signal. When the current in the three-terminal bidirectional controllable switch is reduced to a certain value, the switch is automatically turned off, so the timing of the arrival of the control signal is determined. The on-time of the three-terminal bidirectional controllable switch. The conduction time of the three-terminal bidirectional controllable switch in one power supply cycle is represented by a corresponding angle. Therefore, the three-terminal controllable dimmer 202 processes the high-voltage alternating current supply voltage U1 to output a high-voltage alternating current U2 whose conduction angle is controlled. The electronic transformer 204 detects the conduction angle through the conduction angle detecting module, and generates a first PWM signal Ua such that a frequency and a duty ratio of the first PWM signal Ua and a frequency of the conduction angle signal Same as duty cycle. The first PWM signal Ua is input to the conduction angle modulation module, and is subjected to low-pass filtering to generate a DC voltage signal U _dc , and the DC voltage signal U _dc reflects a DC average value of the first PWM signal Ua. Comparing the DC voltage signal U _dc with a triangular wave signal to generate a second PWM signal Um, the duty ratio of the second PWM signal Um is adjusted by the conduction angle, and the frequency thereof is much higher than The frequency of the conduction angle signal. The second PWM signal Um is input to the converter module to control it to convert the high voltage alternating current U2 into the PWM low voltage direct current U3. The frequency and duty ratio of the PWM low-voltage direct current U3 are consistent with the frequency and duty ratio of the second PWM signal Um, and thus, the duty ratio thereof reflects the conduction angle of the high-voltage alternating current U2, and the amplitude thereof is adjusted. At a predetermined settling value, such as 12V, the WLED driver 206 is powered. When the PWM low voltage direct current U3 is at a high level, the WLED driver 206 provides a constant operating current to the WLED 208; when the PWM low voltage direct current U3 is at a low level, the WLED driver 206 does not supply power to the WLED 208, and no current flows through the WLED 208. . Therefore, the three-terminal controllable dimmer 202 is adjusted to change the conduction angle of the output high-voltage alternating current U2, that is, the duty ratio of the PWM low-voltage direct current U3 output by the electronic transformer 204 can be adjusted, thereby controlling the The average current level provided by the WLED driver 206 for the WLED 208 enables adjustment of the brightness of the WLED 208. Since the frequency and duty ratio of the PWM low-voltage direct current U3 output by the electronic transformer 204 in the embodiment of the present invention are consistent with the frequency and duty ratio of the second PWM signal Um, the frequency thereof is much higher than The frequency of the conduction angle signal is such that the PWM low voltage direct current U3 does not include an alternating current voltage ripple having a frequency of 50 Hz or less, and the WLED tube 208 does not flicker during the dimming process.

In different embodiments of the present invention, the conduction angle detecting module can be implemented by using a plurality of conduction angle detecting circuit structures in the prior art. FIG. 5 is a circuit structural diagram of a conduction angle detecting module according to an embodiment of the present invention. The circuit 500 includes a rectifier circuit 501 and a linear-like regulator circuit 502. Wherein, the rectifier circuit 501 is composed of four high voltage resistant diodes The body D1, D2, D3 and D4 are composed, the series combination of the high voltage resistant diodes D1 and D2 and the series combination of the high voltage resistant diodes D3 and D4 are coupled in parallel between the power supply line L1 and the ground, and are resistant to high voltage. The cathodes of the diodes D1 and D3 are coupled to the power supply line L1, and the anodes of the high voltage resistant diodes D2 and D4 are coupled to the ground, and one end of the high voltage alternating current U2 is coupled to the anode of the high voltage resistant diode D1 and The cathode of the high voltage diode D2 is coupled to the anode of the high voltage diode D3 and the cathode of the high voltage diode D4; the linear regulator circuit 502 includes a first resistor R1. a voltage stabilizing diode D5, a second voltage stabilizing diode D6, a transistor Q1, a second resistor R2 and a capacitor C1, one end of the first resistor R1 is coupled to the power supply line L1, and the other end is The anode of the first voltage stabilizing diode D5 is coupled to the cathode of the second voltage stabilizing diode D6 and the gate of the transistor Q1. The anode of the second Zener diode D6 is coupled to the ground, the drain of the transistor Q1 is coupled to the power supply line L1, and the source thereof is transmitted through the second resistor. R2 is coupled to the ground, the capacitor C1 is coupled in parallel to both ends of the second resistor R2, and the source of the transistor Q1 and the non-ground terminal of the second resistor R2 are used together as the The output of circuit 500. The operation principle of the circuit 500 is as follows: after the high voltage alternating current U2 is rectified via the rectifying circuit 501, the positive half wave remains as it is, and the negative half wave is inverted to a positive half wave, and is loaded on the power supply line L1. The upper line voltage UL1 is as shown in FIG. 6; the linear regulator circuit 502 is powered by the line voltage UL1, when the voltage on the first voltage stabilizing diode D5 reaches its reverse breakdown At a voltage, the voltage on the second Zener diode D6 starts to rise. The output voltage Ua of the conduction angle detecting circuit 500 is equal to the voltage on the voltage stabilizing diode D6 minus the gate-source voltage of the transistor Q1. Since the transistor Q1 operates in the linear region, its gate-source is The voltage is small, so the first PWM signal Ua is close to the voltage on the voltage stabilizing diode D6; when the voltage on the voltage stabilizing diode D6 also reaches its reverse breakdown voltage, the voltage regulator diode D6 The voltage is clamped to its reverse breakdown voltage, and the first PWM signal Ua is also clamped to a potential close to the reverse breakdown voltage of the Zener diode D6 (regulator diode Di6) The reverse breakdown voltage minus the gate-source voltage of transistor Q1. The reverse breakdown voltage of the voltage stabilizing diodes D5 and D6 is generally not large, and the rising edge of the first PWM signal Ua and the three-terminal bidirectional controllable switch of the three-terminal controllable dimmer 202 are basically turned on. Consistently, the falling edge of the first PWM signal Ua is substantially the same as the turn-off timing of the triac, and when the triac is turned off, the line voltage UL1 becomes zero, then The first PWM signal Ua will also jump to zero, so Ua is a pulse signal whose pulse width is consistent with the on-time of the three-terminal bidirectional controllable switch, thus enabling detection of the conduction angle of the high voltage alternating current U2. It should be understood by those skilled in the art that the circuit 500 can also have various equivalent changes, for example, the first voltage stabilizing diode D5 can be removed, and the same conduction angle detecting function can still be realized. The transistor Q1 can also be Other controllable switching devices, such as BJT. In addition, those skilled in the art should understand that in various embodiments of the present invention, a zero-crossing comparator circuit can also be used to replace the linear-like regulator circuit 502 in the circuit 500, and the line voltage UL1 is used. Passing through the zero detection comparator circuit to output the first PWM The signal Ua, once the line voltage UL1 is greater than zero, the Ua signal outputted by the zero-crossing detection comparator circuit jumps to a high level, and once the line voltage UL1 falls to zero, the zero-crossing detection Ua signal output by the comparator circuit The transition to the low level, therefore, the pulse width of the first PWM signal reflects the conduction angle of the high voltage alternating current U2.

In a different embodiment of the present invention, the conduction angle modulation module includes a low pass filter and a PWM comparator, wherein the low pass filter is configured to receive the first PWM signal Ua and convert it into a The DC voltage signal U _dc is received by the PWM comparator and compared with a triangular wave signal to output the second PWM signal Um.

In various embodiments of the invention, the converter module can be any AC-DC converter that converts high voltage alternating current to low voltage direct current.

The three-terminal controllable dimming WLED driving method and the driving circuit of the embodiment of the invention successfully realize the purpose of smoothing flicker-free dimming of the WLED by using the three-terminal controllable dimming device, and can achieve good brightness adjustment of the WLED illumination. effect.

The three-terminal controllable dimming WLED driver circuit control circuit of various embodiments of the present invention can be implemented in a low cost and low complexity manner at the integrated circuit level.

The above description and embodiments of the present invention are merely exemplary WLED driving methods and driving circuits suitable for three-terminal controllable dimmers, and are not intended to limit the scope of the present invention. Variations and modifications to the disclosed embodiments are possible, other possible alternative embodiments and elements in the embodiments Equivalent variations of the components will be apparent to those of ordinary skill in the art. Other variations and modifications of the disclosed embodiments of the invention do not depart from the spirit and scope of the invention.

200‧‧‧ drive circuit

202‧‧‧Three-terminal controllable dimmer

204‧‧‧Electronic transformer

206‧‧‧WLED driver

208‧‧‧WLED tube

100‧‧‧ drive circuit

101‧‧‧Three-terminal controllable dimmer

103‧‧‧Electronic transformer

105‧‧‧Rectifier

107‧‧‧WLED driver

109‧‧‧White LED (WLED)

500‧‧‧ circuits

501‧‧‧Rectifier circuit

502‧‧‧ class linear regulator circuit

The following figures illustrate embodiments of the invention. These figures and embodiments provide some embodiments of the invention in a non-limiting, non-exhaustive manner.

FIG. 1 shows a schematic diagram of a WLED driving circuit using a three-terminal controllable 矽 dimmer in the prior art.

2 is a schematic diagram of a WLED driving circuit suitable for a three-terminal controllable xenon dimmer according to an embodiment of the invention.

3 is a schematic diagram of an electronic transformer circuit in a WLED driving circuit suitable for a three-terminal controllable xenon dimmer according to an embodiment of the invention.

4 is a schematic diagram showing main signal waveforms of a WLED driving circuit suitable for a three-terminal controllable xenon dimmer according to an embodiment of the present invention.

5 is a circuit configuration diagram of a conduction angle detecting module in a WLED driving circuit suitable for a three-terminal controllable xenon dimmer according to an embodiment of the present invention.

FIG. 6 is a schematic diagram showing main signal waveforms of the conduction angle detecting circuit shown in FIG. 5.

200‧‧‧ drive circuit

202‧‧‧Three-terminal controllable dimmer

204‧‧‧Electronic transformer

206‧‧‧WLED driver

208‧‧‧WLED tube

Claims (19)

A white LED driving circuit suitable for a three-terminal controllable dimmer, comprising: a three-terminal controllable dimmer, an electronic transformer, and a white LED driver, wherein the three-terminal controllable dimmer is used for Coupling a high-voltage AC power supply to output a high-voltage alternating current with controlled conduction angle; the electronic transformer is configured to receive the high-voltage alternating current to output a pulse width modulated low-voltage direct current; and the white LED driver is configured to receive the pulse width modulation Converting a low-voltage direct current to output a white LED driving signal, wherein the electronic transformer detects a conduction angle of the high-voltage alternating current, and adjusts a duty ratio of the output pulse width modulated low-voltage direct current based on the conduction angle, the electronic transformer The method includes: a conduction angle detecting module, a conduction angle modulation module, and a converter module, wherein the conduction angle detecting module is configured to detect a conduction angle of the high voltage alternating current, and based on the conduction angle, to generate a first pulse a width modulation signal; the conduction angle modulation module is configured to receive the first pulse width modulation signal, and filter the same to generate the first pulse a DC voltage signal of a DC average value of the width modulation signal, and comparing the DC voltage signal with the triangular wave signal to output a second pulse width modulation signal; and the converter module is modulated by the second pulse width modulation signal Controlled to convert the high voltage alternating current into the pulse width modulated low voltage direct current. The white LED driving circuit of claim 1, wherein the frequency and duty ratio of the first pulse width modulation signal are The frequency of the conduction angle signal is consistent with the duty ratio; and the duty ratio of the second pulse width modulation signal is adjusted by the conduction angle signal, and the frequency thereof is higher than the frequency of the conduction angle signal. The white LED driving circuit of claim 1, wherein the conduction angle detecting module comprises a rectifying circuit and a linear regulator circuit, wherein the rectifying circuit is configured to receive the high voltage alternating current and rectify the same a high voltage direct current; and the linear regulator circuit comprising at least one voltage stabilizing diode and a controllable switch, the cathode of the voltage stabilizing diode being coupled to the high voltage direct current via a first resistor, and an anode system The gate of the controllable switch is coupled to the cathode of the voltage stabilizing diode, the drain of the diode is coupled to the high voltage direct current, and the source thereof is coupled to the ground via the second resistor. The source of the controllable switch is used as the output of the conduction angle detection module. The white LED driving circuit of claim 1, wherein the conduction angle detecting module comprises a rectifying circuit and a zero-crossing detecting comparator circuit, wherein the rectifying circuit is configured to receive the high-voltage alternating current and rectify the same a high voltage direct current; and the zero crossing detection comparator circuit for receiving and processing the high voltage direct current to output the first pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal It is a high level, and when the high voltage direct current is reduced to zero, the first pulse width modulation signal is at a low level. White LED driver as described in claim 1 or 3 The circuit, wherein the conduction angle modulation module comprises a low pass filter and a pulse width modulation comparator, wherein the low pass filter is configured to receive the first pulse width modulation signal and convert it into the a DC voltage signal; and the pulse width modulation comparator for comparing the DC voltage signal with the triangular wave signal to output the second pulse width modulation signal. The white LED driving circuit of claim 1, wherein the converter module is an AC-DC converter that converts high voltage alternating current into low voltage direct current. A white LED driving method suitable for a three-terminal controllable dimming device, comprising: receiving a high-voltage alternating current power supply to output a high-voltage alternating current with a conduction angle controlled; converting the high-voltage alternating current into a pulse width modulated low-voltage direct current; The pulse width modulation low voltage direct current input white LED driver adjusts the driving white LED; wherein the method further comprises: detecting a conduction angle of the high voltage alternating current, and adjusting a duty ratio of the pulse width modulation low voltage direct current based on the conduction angle The step of converting the high voltage alternating current into the pulse width modulated low voltage direct current comprises: detecting a conduction angle of the high voltage alternating current, and generating a first pulse width modulation signal; filtering the first pulse width modulation signal to Produce a reflection of the first a DC voltage signal of a DC average of the pulse width modulation signal; comparing the DC voltage signal with the triangular wave signal to generate a second pulse width modulation signal; and controlling the second pulse width modulation signal based on the second pulse width modulation signal The high voltage alternating current is converted into the pulse width modulated low voltage direct current. The white LED driving method of claim 7, wherein a frequency and a duty ratio of the first pulse width modulation signal are consistent with a frequency and a duty ratio of the conduction angle signal; and the second pulse width The duty cycle of the modulated signal is adjusted by the conduction angle signal, the frequency of which is higher than the frequency of the conduction angle signal. The white LED driving method of claim 7, wherein the conduction angle of the high voltage alternating current is detected by a conduction angle detecting module, wherein the conduction angle detecting module comprises a rectifier circuit and a linear regulator circuit, wherein The rectifier circuit is configured to receive the high voltage alternating current and rectify it into high voltage direct current; and the linear regulator circuit includes at least one voltage stabilizing diode and a controllable switch, the cathode of the voltage stabilizing diode The high voltage direct current is coupled to the high voltage direct current through a first resistor, the anode of the controllable switch is coupled to the cathode of the voltage stabilizing diode, and the drain is coupled to the high voltage direct current. The source is coupled to the ground via a second resistor, and the source of the controllable switch is used as an output of the conduction angle detecting module. The white LED driving method according to claim 7, wherein the conduction angle detecting module detects the high voltage alternating current guiding a pass angle, the conduction angle detecting module includes a rectifying circuit and a zero-crossing detecting comparator circuit, wherein the rectifying circuit is configured to receive the high-voltage alternating current and rectify the same into a high-voltage direct current; and the zero-crossing detecting comparator circuit Receiving and processing the high voltage direct current to output the first pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal is at a high level, and when the high voltage direct current voltage is zero, The first pulse width modulation signal is at a low level. The white LED driving method of claim 7, wherein the first pulse width modulation signal is filtered by a low pass filter. The white LED driving method of claim 7, wherein the DC voltage signal and the triangular wave signal are received by a pulse width modulation comparator to output the second pulse width modulation signal. The white LED driving method of claim 7, wherein the high voltage alternating current and the second pulse width modulation signal are received by an AC-DC converter to convert the high voltage alternating current into the pulse width modulation. Low voltage DC. An electronic transformer for receiving high-voltage alternating current outputted by a three-terminal controllable dimmer and outputting a pulse width modulated low-voltage direct current, characterized in that comprising a conduction angle detecting module for detecting a conduction angle of the high-voltage alternating current And a control module that adjusts the output based on the detected conduction angle signal a pulse width modulation low-voltage direct current duty cycle; wherein the control module includes a conduction angle modulation module and a converter module; the conduction angle detection module is configured to generate a first pulse based on the detected conduction angle signal a width modulation signal; the conduction angle modulation module is configured to receive the first pulse width modulation signal, and filter the same to generate a DC voltage signal reflecting a DC average value of the first pulse width modulation signal, and The DC voltage signal is compared with the triangular wave signal to output a second pulse width modulation signal; and the converter module is controlled by the second pulse width modulation signal to convert the high voltage alternating current into the pulse width modulation Low voltage DC. The electronic transformer of claim 14, wherein a frequency and a duty ratio of the first pulse width modulation signal are consistent with a frequency and a duty ratio of the conduction angle signal; and the second pulse width modulation The duty cycle of the signal is regulated by the conduction angle signal, the frequency of which is higher than the frequency of the conduction angle signal. The electronic transformer of claim 14, wherein the conduction angle detecting module comprises a rectifying circuit and a linear regulator circuit, wherein the rectifying circuit is configured to receive the high voltage alternating current and rectify it into a high voltage And a linear regulator circuit comprising: at least one voltage stabilizing diode and a controllable switch, wherein the cathode of the voltage stabilizing diode is coupled to the high voltage direct current via a first resistor, and the anode is coupled To the ground, the gate of the controllable switch is coupled to the cathode of the voltage stabilizing diode, and the drain is coupled to the high voltage direct current. The source is coupled to ground via a second resistor, and the source of the controllable switch is used as an output of the conduction angle detecting module. The electronic transformer of claim 14, wherein the conduction angle detecting module comprises a rectifying circuit and a zero-crossing detecting comparator circuit, wherein the rectifying circuit is configured to receive the high-voltage alternating current and rectify it into a high voltage a direct current detecting comparator circuit for receiving and processing the high voltage direct current to output the first pulse width modulation signal, and when the high voltage direct current is greater than zero, the first pulse width modulation signal is high The first pulse width modulation signal is at a low level when the high voltage direct current is reduced to zero. The electronic transformer of claim 14, wherein the conduction angle modulation module comprises a low pass filter and a pulse width modulation comparator, wherein the low pass filter is configured to receive the first pulse The width modulation signal is converted into the DC voltage signal; and the pulse width modulation comparator is configured to compare the DC voltage signal with the triangular wave signal to output the second pulse width modulation signal. The electronic transformer of claim 14, wherein the converter module is an AC-DC converter that converts high voltage alternating current into low voltage direct current.