A thyristor dimming device of LED driving power supply

Abstract

The application discloses a thyristor dimming device of an LED driving power supply, which comprises a voltage conversion unit, a rectification filter unit, a first switch unit, a first filter unit, a first voltage stabilization unit, a phase detection module and a control unit. A voltage conversion output of a front-stage circuit is subjected to cut-phase control to output a steamed-bun wave. A reflected voltage of the voltage conversion unit is rectified into a pulse wave by the rectification unit. The pulse wave is divided into voltages by a voltage distribution unit to drive the second switch unit, so that the pulse wave is converted into a square wave with a duty cycle. The control unit outputs a corresponding driving waveform to the first switch unit according to the size of the duty cycle of the square wave. The first switch unit is driven to perform voltage chopping, so that the output current is changed in the range of 1-100% to realize dimming. The phase detection module cooperates with the rectification filter unit to filter out the noise in the voltage signal, so as to improve the detection precision. The first filter unit cooperates with the first switch unit to fill in the energy of the missing waveform, so that the output current is smoother.

Description

Technical Field

[0001] This invention relates to the field of thyristor dimming technology, and in particular to a thyristor dimming device for an LED driver power supply. Background Technology

[0002] Commercially available LED driver power supplies generally employ a silicon controlled rectifier (SCR) phase-cut dimming method. This method adjusts the output current of the LED light source by detecting the phase angle output of the SCR. Due to its low cost and ease of dimming, it is widely used in the lighting technology field. However, during use, it has been found that when the SCR dimmer adjusts the SCR's conduction, the AC mains voltage is applied almost instantaneously to the LC input filter of the LED driver power supply. This causes a voltage step across the inductor, leading to oscillations. Furthermore, the frequent phase angle switching makes it impossible for the LED driver power supply to maintain a stable output, resulting in slight flickering and audible noise. Existing solutions typically reduce this oscillation by incorporating EMI filter circuits in the system. However, commercially available EMI filter circuits suffer from complex structures and inaccurate phase detection.

[0003] The purpose of this application is to provide a silicon controlled rectifier (SCR) dimming device for an LED driver power supply that solves at least one of the above-mentioned problems. Summary of the Invention

[0004] The purpose of this invention is to provide a thyristor dimming device for an LED driver power supply, which is designed to overcome the shortcomings of the above-mentioned technologies.

[0005] The present invention provides a silicon controlled rectifier (SCR) dimming device for an LED driver power supply, comprising a transformer unit, a rectifier and filter unit, a first switching unit, a first filter unit, a first voltage regulator unit, a phase detection module, a control unit, and a first voltage terminal;

[0006] The input terminal of the transformer unit is electrically connected to the pre-amplifier circuit, and the output terminal of the transformer unit is electrically connected to the rectifier filter unit, the first voltage regulator unit, and the phase detection module, respectively. The rectifier filter unit is electrically connected to the input terminal of the first filter unit through the first switch unit. The output terminal of the first filter unit is electrically connected to the light source assembly. The phase detection module and the first switch unit are electrically connected to the control unit, respectively. The rectifier filter unit, the first filter unit, and the first voltage regulator unit are electrically connected to the first voltage terminal, respectively.

[0007] The phase detection module includes a rectifier unit, a voltage distribution unit, and a second switching unit that are connected in sequence; the input terminal of the rectifier unit is electrically connected to the output terminal of the transformer unit, the voltage distribution unit is electrically connected to the first voltage regulator unit, and the second switching unit is electrically connected to the control unit.

[0008] The pre-amplifier circuit performs voltage conversion and outputs a phase-cutting controlled swivel wave. The reflected voltage of the transformer unit is rectified into a pulse wave by the rectifier unit. The pulse wave is divided by the voltage distribution unit to drive the second switching unit, converting the pulse wave into a square wave with a duty cycle. The control unit outputs a corresponding drive waveform to the first switching unit according to the magnitude of the square wave duty cycle. The first switching unit is driven to perform voltage chopping, realizing dimming by varying the output current within the range of 1-100%.

[0009] Preferably, the system also includes a second voltage regulator unit, which is electrically connected to the control unit and the first voltage terminal.

[0010] Preferably, the system also includes a current acquisition unit and an overcurrent protection unit. The current acquisition unit is located between the rectifier and filter unit and the first switch unit. The overcurrent protection unit is electrically connected to the first switch unit, the control unit, and the second voltage regulator unit, respectively.

[0011] Preferably, it also includes a reverse connection protection unit, which is connected in parallel to both ends of the input terminal of the first filter unit.

[0012] Preferably, the rectifier-filter unit includes a first diode, a first resistor, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; the first switching unit includes a second resistor and a first switching transistor; the first filtering unit includes a first inductor; and the current acquisition unit includes a sampling resistor.

[0013] The first resistor and the first capacitor are connected in series and then connected in parallel across the two ends of the first diode. The positive terminal of the first diode is electrically connected to the first terminal of the transformer unit output. The negative terminal of the first diode is connected in parallel with the second terminal of the transformer unit output in sequence, followed by the second capacitor, the third capacitor, and the fourth capacitor. The second terminal of the transformer unit output is electrically connected to the first ground terminal, and the negative terminal of the first diode is electrically connected to the first voltage terminal.

[0014] The first end of the sampling resistor is electrically connected to the first ground terminal and one end of the fourth capacitor, the second end of the sampling resistor is electrically connected to the second ground terminal and the first end of the first switching transistor, the control terminal of the first switching transistor is electrically connected to the control unit, a second resistor is connected in series between the control terminal of the first switching transistor and its first end, the second end and the first voltage terminal of the first switching transistor are respectively connected to the input terminal of the first inductor, and the output terminal of the first inductor is electrically connected to the light source assembly.

[0015] Preferably, the first voltage regulator unit includes a second diode, a third diode, a three-terminal Zener diode, an optocoupler, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor.

[0016] The positive terminal of the second diode is electrically connected to the first terminal of the transformer unit output. An eighth capacitor and a third resistor are connected in parallel between the negative terminal of the second diode and the first ground terminal. A third diode and a three-terminal Zener diode are also connected in series between the negative terminal of the second diode and the first ground terminal. A fourth resistor and an optocoupler are connected in series between the negative terminal of the second diode and the negative terminal of the three-terminal Zener diode. A sixth resistor, a seventh resistor, and an eighth resistor are connected in series between the first voltage terminal and the first ground terminal. A fifth resistor and a fifth capacitor are connected in series between the control terminal of the three-terminal Zener diode and its negative terminal. The two ends of the sixth capacitor are electrically connected to the negative terminal of the three-terminal Zener diode and the seventh resistor, respectively. The control terminal of the three-terminal Zener diode is electrically connected to the connection point of the seventh and eighth resistors. The seventh capacitor is connected in parallel across the eight resistors.

[0017] Preferably, the rectifier unit includes a fourth diode, the voltage distribution unit includes a ninth resistor, a tenth resistor, and a ninth capacitor, and the second switching unit includes a second switching transistor, a fifth diode, an eleventh resistor, and a twelfth resistor.

[0018] The negative terminal of the fourth diode is electrically connected to the first terminal of the transformer unit output and the positive terminal of the second diode. The positive terminal of the fourth diode is connected in series with the tenth resistor and the twelfth resistor and then electrically connected to the control unit. A ninth resistor and a ninth capacitor are connected in parallel between the positive terminal of the fourth diode and the first ground terminal. The control terminal of the second switch is electrically connected to the connection point of the tenth resistor and the twelfth resistor. A fifth diode is connected in series between the control terminal of the second switch and the first ground terminal. An eleventh resistor is connected in series between the first terminal of the second switch and the control unit. The second terminal of the second switch is connected to the first ground terminal.

[0019] Preferably, the second voltage regulator unit includes a first transistor, a sixth diode, a thirteenth resistor, and a tenth capacitor;

[0020] A thirteenth resistor is connected in series between the control terminal and the first voltage terminal of the first transistor, a sixth diode is connected in series between the control terminal and the first ground terminal of the first transistor, the first terminal of the first transistor is electrically connected to the first voltage terminal, a tenth capacitor is connected in series between the second terminal of the first transistor and the first ground terminal, and the second terminal of the first transistor is electrically connected to the control unit.

[0021] Preferably, the overcurrent protection unit includes a second transistor, a third transistor, a seventh diode, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, an eleventh capacitor, and a twelfth capacitor.

[0022] The control terminal of the second transistor is connected in series with the eighteenth and seventeenth resistors and electrically connected to the second terminal of the first transistor. The two ends of the eighteenth resistor are connected in series with the seventh diode and the sixteenth resistor. The connection point of the sixteenth resistor and the seventh diode is electrically connected to the second ground terminal. The control terminal and the first terminal of the second transistor are electrically connected to the first terminal and the control terminal of the third transistor, respectively. The control terminal and the second terminal of the second transistor are connected in series with the twelfth capacitor. The second terminal of the second transistor is electrically connected to the first ground terminal. The control terminal and the second terminal of the third transistor are connected in parallel with the eleventh capacitor and the fifteenth resistor. The second terminal of the third transistor is connected in series with the control unit with the fourteenth resistor. The second terminal of the third transistor is electrically connected to the first switching unit.

[0023] This invention provides a thyristor dimming device for an LED driver power supply. Through structural design, the transformer unit isolates mains noise, and the square wave signal generated after rectification and voltage division of the reflected voltage exhibits high stability and strong anti-interference capabilities. A phase detection module, in conjunction with a rectifier and filter unit, filters out noise in the voltage signal, reducing errors and improving phase detection accuracy. A first filter unit, in conjunction with a first switch unit, fills in missing waveform energy, resulting in a smoother output current. The rectification, filtering, phase detection, and voltage regulation control employ a modular design, resulting in high system integration. This allows for compatibility with various LED loads and simplifies the circuit structure. It solves the problem of slight LED flicker caused by output current following input changes in low-cost dimmers and also provides overcurrent protection. Attached Figure Description

[0024] Figure 1 This is a structural principle block diagram of a thyristor dimming device for an LED driver power supply provided by the present invention.

[0025] Figure 2 yes Figure 1 The circuit schematic in the image.

[0026] Figure 3 This is a signal waveform diagram of a thyristor dimming device for an LED driver power supply provided by the present invention.

[0027] Figure 4 This is a schematic diagram of a square wave with a duty cycle of 50% and its corresponding driving waveform provided by the present invention.

[0028] The attached figures are labeled as follows:

[0029] 1. Transformer unit; 2. Rectifier and filter unit; 3. First switching unit; 4. First filter unit; 5. First voltage regulator unit; 6. Phase detection module; 61. Rectifier unit; 62. Voltage distribution unit; 63. Second switching unit; 7. Control unit; 8. Second voltage regulator unit; 9. Current acquisition unit; 10. Overcurrent protection unit; 11. Reverse connection protection unit; 100. Pre-amplifier circuit; 200. Light source assembly; 300. First voltage terminal;

[0030] D17, First Diode; R36, First Resistor; C13, First Capacitor; CE5, Second Capacitor; CE6, Third Capacitor; CE7, Fourth Capacitor; R42, Second Resistor; Q3, First Switch; LF3, First Inductor; R16, Sampling Resistor; D13, Second Diode; D14, Third Diode; U4, Zener Diode; U1A, Optocoupler; R38, Third Resistor; R39, Fourth Resistor; R40, Fifth Resistor; R47, Sixth Resistor; R47A, Seventh Resistor; R48, Eighth Resistor; C18, Fifth Capacitor; C29, Sixth Capacitor; C30, Seventh Capacitor; CE3, Eighth Capacitor; D15, Fourth Diode; R34, Ninth Resistor; R41, Tenth Resistor; Resistors; C11, Ninth Capacitor; Q2, Second Switch; D11, Fifth Diode; R35, Eleventh Resistor; R50, Twelfth Resistor; Q8, First Transistor; ZD6, Sixth Diode; R60, Thirteenth Resistor; C28, Tenth Capacitor; Q4, Second Transistor; Q7, Third Transistor; D19, Seventh Diode; R32, Fourteenth Resistor; R43, Fifteenth Resistor; R44, Sixteenth Resistor; R57, Seventeenth Resistor; R58, Eighteenth Resistor; C26, Eleventh Capacitor; C27, Twelfth Capacitor; D21, Eighth Diode; R45, Nineteenth Resistor; TR1, Transformer; U3, Control Chip; GND, First Ground Terminal; GND1, Second Ground Terminal. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0032] In this embodiment, as Figure 1-2As shown, this invention discloses a silicon controlled rectifier (SCR) dimming device for an LED driver power supply, comprising a transformer unit 1, a rectifier-filter unit 2, a first switching unit 3, a first filtering unit 4, a first voltage regulator unit 5, a phase detection module 6, a control unit 7, and a first voltage terminal 300. The input terminal of the transformer unit 1 is electrically connected to the pre-amplifier circuit 100, and the output terminal of the transformer unit 1 is electrically connected to the rectifier-filter unit 2, the first voltage regulator unit 5, and the phase detection module 6. The rectifier-filter unit 2 is electrically connected to the input terminal of the first filtering unit 4 via the first switching unit 3, and the output terminal of the first filtering unit 4 is electrically connected to the light source assembly 200. The phase detection module 6 and the first switching unit 3 are electrically connected to the control unit 7, and the rectifier-filter unit 2, the first filtering unit 4, and the first voltage regulator unit 5 are electrically connected to the first voltage terminal 300. The first voltage terminal 300 is obtained by AC power conversion and voltage reduction.

[0033] The phase detection module 6 includes a rectifier unit 61, a voltage distribution unit 62, and a second switch unit 63 connected in sequence. The input terminal of the rectifier unit 61 is electrically connected to the output terminal of the transformer unit 1, the voltage distribution unit 62 is electrically connected to the first voltage regulator unit 5, and the second switch unit 63 is electrically connected to the control unit 7.

[0034] The pre-amplifier circuit 100 performs voltage conversion and outputs a phase-cutting controlled swivel wave. The reflected voltage of the transformer unit 1 is rectified into a pulse wave by the rectifier unit 61. The pulse wave is divided by the voltage distribution unit 62 to drive the second switching unit 63, converting the pulse wave into a square wave with a duty cycle. The control unit 7 outputs the corresponding drive waveform to the first switching unit 3 according to the size of the square wave duty cycle. The first switching unit 3 is driven to perform voltage chopping, so that the output current can be varied in the range of 1-100% for dimming.

[0035] The thyristor dimming device of the LED driver power supply also includes a second voltage regulator unit 8, a current acquisition unit 9, an overcurrent protection unit 10, and a reverse connection protection unit 11. The second voltage regulator unit 8 is electrically connected to the control unit 7 and the first voltage terminal 300, respectively. The current acquisition unit 9 is located between the rectifier filter unit 2 and the first switch unit 3. The overcurrent protection unit 10 is electrically connected to the first switch unit 3, the control unit 7, and the second voltage regulator unit 8, respectively. The reverse connection protection unit 11 is connected in parallel to both ends of the input terminal of the first filter unit 4.

[0036] The first voltage regulator unit 5 provides a stable power supply voltage to the control unit 7, and the second voltage regulator unit 8 linearly adjusts the output voltage through transistors to suppress voltage fluctuations and provide an independent and stable power supply environment for the internal circuit of the control unit 7. The two work together to achieve voltage regulation and improve the reliability of the system.

[0037] like Figure 2As shown, the rectifier-filter unit 2 includes a first diode D17, a first resistor R36, a first capacitor C13, a second capacitor CE5, a third capacitor CE6, and a fourth capacitor CE7; the first switching unit 3 includes a second resistor R42 and a first switching transistor Q3; the first filtering unit 4 includes a first inductor LF3; the current acquisition unit 9 includes a sampling resistor R16; and the reverse connection protection unit 11 includes an eighth diode D21. The transformer unit 1 includes a transformer TR1, and the control unit 7 includes a control chip U3.

[0038] The first resistor R36 and the first capacitor C13 are connected in series and then in parallel across the first diode D17. The anode of the first diode D17 is electrically connected to the first terminal of the output of transformer TR1. The cathode of the first diode D17 is connected in parallel with the second terminal of the output of transformer TR1, followed by the second capacitor CE5, the third capacitor CE6, and the fourth capacitor CE7. The second terminal of the output of transformer TR1 is electrically connected to the first ground terminal GND, and the cathode of the first diode D17 is electrically connected to the first voltage terminal 300. The first diode D17, along with the second capacitor CE5, the third capacitor CE6, and the fourth capacitor CE7, constitute a π-type filter, which can improve rectification efficiency and reduce input voltage ripple.

[0039] The first end of sampling resistor R16 is electrically connected to the first ground terminal GND and one end of the fourth capacitor CE7. The second end of sampling resistor R16 is electrically connected to the second ground terminal GND1 and the first end of the first switching transistor Q3. The control terminal of the first switching transistor Q3 is electrically connected to the control unit 7. A second resistor R42 is connected in series between the control terminal and the first end of the first switching transistor Q3. The second end of the first switching transistor Q3 and the first voltage terminal 300 are connected to the input terminal of the first inductor LF3. The output terminal of the first inductor LF3 is electrically connected to the light source assembly 200. An eighth diode D21 is connected in series across the input terminals of the first inductor LF3 to prevent damage to electronic components in the circuit when the power supply is reversed. It also absorbs the reverse electromotive force generated when there is freewheeling current in the first inductor LF3, preventing voltage spikes from breaking down the first switching transistor Q3. The first switching transistor Q3 is a MOSFET.

[0040] The first voltage regulator unit 5 includes a second diode D13, a third diode D14, a three-terminal Zener diode U4, an optocoupler U1A, a third resistor R38, a fourth resistor R39, a fifth resistor R40, a sixth resistor R47, a seventh resistor R47A, an eighth resistor R48, a fifth capacitor C18, a sixth capacitor C29, a seventh capacitor C30, and an eighth capacitor CE3.

[0041] The positive terminal of the second diode D13 is electrically connected to the first terminal of the transformer TR1 output. A parallel eighth capacitor CE3 and a third resistor R38 are connected between the negative terminal of the second diode D13 and the first ground terminal GND. A series connection is also established between the negative terminal of the second diode D13 and the first ground terminal GND, consisting of a third diode D14 and a three-terminal Zener diode U4. A fourth resistor R39 and the emitter of the optocoupler U1A are connected in series between the negative terminal of the second diode D13 and the negative terminal of the three-terminal Zener diode U4. The first voltage terminal is 300... A sixth resistor R47, a seventh resistor R47A, and an eighth resistor R48 are connected in series between the first ground terminal GND and the third ground terminal GND. A fifth resistor R40 and a fifth capacitor C18 are connected in series between the control terminal of the three-terminal Zener diode U4 and its negative terminal. The two ends of the sixth capacitor C29 are electrically connected to the negative terminal of the three-terminal Zener diode U4 and the seventh resistor R47A, respectively. The control terminal of the three-terminal Zener diode U4 is electrically connected to the connection point of the seventh resistor R47A and the eighth resistor R48. The seventh capacitor C30 is connected in parallel across the eight resistor R48.

[0042] The receiving end of the optocoupler U1A is connected to the preamplifier circuit 100. Voltage feedback is achieved through the three-terminal Zener diode U4 and the optocoupler U1A. The preamplifier circuit 100 adjusts the voltage at the input end of the transformer unit 1 to suppress output voltage fluctuations and ensure the accuracy of phase detection. The optocoupler U1A isolates the high-voltage side and the low-voltage side of the transformer unit 1 to achieve isolation protection. The fifth capacitor C18 and the fifth resistor R40 form a phase compensation network to avoid oscillation in the voltage regulation loop.

[0043] The rectifier unit 61 includes a fourth diode D15, the voltage distribution unit 62 includes a ninth resistor R34, a tenth resistor R41, and a ninth capacitor C11, and the second switching unit 63 includes a second switching transistor Q2, a fifth diode D11, an eleventh resistor R35, and a twelfth resistor R50.

[0044] The cathode of the fourth diode D15 is electrically connected to the first terminal of the output of transformer TR1 and the anode of the second diode D13. The anode of the fourth diode D15 is connected in series with the tenth resistor R41 and the twelfth resistor R50, and then electrically connected to the control unit 7. A ninth resistor R34 and a ninth capacitor C11 are connected in parallel between the anode of the fourth diode D15 and the first ground terminal GND. The control terminal of the second switch Q2 is electrically connected to the connection point of the tenth resistor R41 and the twelfth resistor R50. The fifth diode D11 is connected in series between the control terminal of the second switch Q2 and the first ground terminal GND. An eleventh resistor R35 is connected in series between the first terminal of the second switch Q2 and the control unit 7. The second terminal of the second switch Q2 is connected to the first ground terminal GND. Among these, the tenth resistor R41 is a pull-up resistor, the ninth resistor R34 is a pull-down resistor, and the second switch Q2 is a MOSFET.

[0045] The voltage distribution unit 62 can be adapted to different transformer output voltages, ensuring that the voltage signal amplitude matches the input level of the control unit 7. The ninth capacitor C11 filters high-frequency noise and reduces the zero-crossing detection error of the second switch Q2.

[0046] The second voltage regulator unit 8 includes a first transistor Q8, a sixth diode ZD6, a thirteenth resistor R60, and a tenth capacitor C28. The thirteenth resistor R60 is connected in series between the control terminal of the first transistor Q8 and the first voltage terminal 300. The sixth diode ZD6 is connected in series between the control terminal of the first transistor Q8 and the first ground terminal GND. The first terminal of the first transistor Q8 is electrically connected to the first voltage terminal 300. The tenth capacitor C28 is connected in series between the second terminal of the first transistor Q8 and the first ground terminal GND. The second terminal of the first transistor Q8 is electrically connected to the control unit 7. The second terminal of the first transistor Q8 is also electrically connected to the control unit 7 through a nineteenth resistor R45. The first transistor Q8 and the sixth diode ZD6 form a linear voltage regulator. Connecting the enable terminal of the control unit 7 through the nineteenth resistor R45 allows for remote shutdown of the first transistor Q8.

[0047] like Figure 3 As shown, when the conduction angle of the thyristor dimmer is adjusted, the AC sine wave A1 is rectified by the rectifier bridge and converted into a dome wave (waveform A2). This dome wave is then phase-cut modulated and converted into a phase-cut dome wave (waveform A3). The phase-cut dome wave A3 is then rectified by the fourth diode D15 and converted into a pulse wave (waveform A4). Finally, after driving the second switch Q2 to conduct, a square wave with a duty cycle is output (waveform A5). The duty cycle of the square wave is related to the phase angle; the larger the phase angle, the smaller the duty cycle. The specific amplitude of the square wave is determined by the control voltage of the control unit 7. Therefore, the phase angle can be determined based on the duty cycle of the square wave. The control unit 7 outputs a drive waveform based on the square wave. Figure 4 The corresponding waveform is a square wave with a duty cycle of 50% and its corresponding driving waveform.

[0048] like Figure 2As shown, the reflected voltage of transformer TR1 is rectified by the fourth diode D15. The tenth resistor R41 and the ninth resistor R34 in the voltage distribution unit 62 divide the voltage to drive the second switch Q2, which is used to determine the high and low level information at the DIM port of the control chip U3. Since the voltage rectified by the fourth diode D15 is filtered out by the delay of the first capacitor C13, and the voltage rectified by the fourth diode D15 is a pulse waveform, the conduction waveform driving the second switch Q2 is a square wave with a duty cycle. By adjusting the size of the duty cycle of the pulse waveform, the high and low level information of the DIM port of the control chip U3 is identified. The control chip U3 obtains the square wave with a duty cycle through internal calculation, and outputs the corresponding drive waveform to the first switch Q3 according to the size of the square wave duty cycle. The fourteenth resistor R32 drives the first switch Q3 to conduct and perform voltage chopping, thereby realizing the dimming of the output current within the range of 1-100%.

[0049] The overcurrent protection unit 10 includes a second transistor Q4, a third transistor Q7, a seventh diode D19, a fourteenth resistor R32, a fifteenth resistor R43, a sixteenth resistor R44, a seventeenth resistor R57, an eighteenth resistor R58, an eleventh capacitor C26, and a twelfth capacitor C27.

[0050] The control terminal of the second transistor Q4 is connected in series with the eighteenth resistor R58 and the seventeenth resistor R57, and is electrically connected to the second terminal of the first transistor Q8. The two ends of the eighteenth resistor R58 are connected in series with the seventh diode D19 and the sixteenth resistor R44. The connection point of the sixteenth resistor R44 and the seventh diode D19 is electrically connected to the second ground terminal GND1. The control terminal and the first terminal of the second transistor Q4 are electrically connected to the first terminal and the control terminal of the third transistor Q7, respectively. The twelfth capacitor C27 is connected in series between the control terminal and the second terminal of the second transistor Q4. The second terminal of the second transistor Q4 is electrically connected to the first ground terminal GND. The eleventh capacitor C26 and the fifteenth resistor R43 are connected in parallel between the control terminal and the second terminal of the third transistor Q7. The fourteenth resistor R32 is connected in series between the second terminal of the third transistor Q7 and the control unit 7. The second terminal of the third transistor Q7 is electrically connected to the control terminal of the first switch transistor Q3 in the first switch unit 3.

[0051] The output current of the thyristor dimming device is detected in real time by sampling resistor R16. The voltage drop across sampling resistor R16 provides a voltage difference to the base of the second transistor Q4. When the base-emitter voltage difference of the second transistor Q4 is greater than 0.7V, the collector-emitter junction of the second transistor Q4 is turned on, pulling the drive waveform low through the fifteenth resistor R43, thereby turning off the PWM waveform and turning off the first switching transistor Q3, realizing overcurrent protection. After the overcurrent is released, the system can automatically recover without manual intervention under normal circumstances.

[0052] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A thyristor dimming device for an LED driving power supply, characterized in that: The application relates to a voltage stabilizing circuit, which comprises a voltage transformation unit (1), a rectification filter unit (2), a first switch unit (3), a first filter unit (4), a first voltage stabilizing unit (5), a phase detection module (6), a control unit (7) and a first voltage terminal (300). The input end of the voltage transformation unit (1) is electrically connected with a front-stage circuit (100), the output end of the voltage transformation unit (1) is electrically connected with the rectification filter unit (2), the first voltage stabilizing unit (5) and the phase detection module (6), the rectification filter unit (2) is electrically connected with the input end of the first filter unit (4) through the first switch unit (3), the output end of the first filter unit (4) is electrically connected with a light source assembly (200), the phase detection module (6) and the first switch unit (3) are electrically connected with the control unit (7) respectively, and the rectification filter unit (2), the first filter unit (4) and the first voltage stabilizing unit (5) are electrically connected with the first voltage terminal (300) respectively. The phase detection module (6) comprises a rectification unit (61), a voltage distribution unit (62) and a second switch unit (63) which are electrically connected in sequence, the input end of the rectification unit (61) is electrically connected with the output end of the voltage transformation unit (1), the voltage distribution unit (62) is electrically connected with the first voltage stabilizing unit (5), and the second switch unit (63) is electrically connected with the control unit (7). The front-stage circuit (100) converts and outputs a phase-cut controlled steamed-bun wave, the reflected voltage of the voltage transformation unit (1) is rectified into a pulse wave by the rectification unit (61), the pulse wave is divided by the voltage distribution unit (62) to drive the second switch unit (63), the pulse wave is converted into a square wave with a duty ratio, the control unit (7) outputs a corresponding driving waveform to the first switch unit (3) according to the size of the duty ratio of the square wave, the first switch unit (3) is driven to perform voltage chopping, and the output current is changed in the range of 1-100% to realize dimming.

2. The silicon controlled rectifier dimming device for an LED driving power supply according to claim 1, wherein: The application further comprises a second voltage stabilizing unit (8), which is electrically connected with the control unit (7) and the first voltage terminal (300) respectively.

3. The LED driving power supply's thyristor dimming device according to claim 2, wherein: The application further comprises a current collecting unit (9) and an overcurrent protection unit (10), the current collecting unit (9) is arranged between the rectification filter unit (2) and the first switch unit (3), and the overcurrent protection unit (10) is electrically connected with the first switch unit (3), the control unit (7) and the second voltage stabilizing unit (8) respectively.

4. The LED driving power supply's thyristor dimming device according to claim 1, wherein: The application further comprises an anti-reverse connection unit (11), which is connected in parallel to both ends of the input end of the first filter unit (4).

5. The LED driving power supply's thyristor dimming device according to claim 3, wherein: The rectification filter unit (2) comprises a first diode (D17), a first resistor (R36), a first capacitor (C13), a second capacitor (CE5), a third capacitor (CE6) and a fourth capacitor (CE7), the first switch unit (3) comprises a second resistor (R42) and a first switch tube (Q3), the first filter unit (4) comprises a first inductor (LF3), and the current collecting unit (9) comprises a sampling resistor (R16). The first resistance (R36), the first capacitor (C13) are connected in series and are connected in parallel between the two ends of the first diode (D17), the positive electrode of the first diode (D17) is electrically connected with the first end of the output end of the voltage conversion unit (1), the second end of the output end of the voltage conversion unit (1) is electrically connected with the first ground end (GND), the negative electrode of the first diode (D17) is electrically connected with the first voltage end (300), the second end of the output end of the voltage conversion unit (1) is electrically connected with the second end of the fourth capacitor (CE7) in sequence, the second end of the output end of the voltage conversion unit (1) is electrically connected with the second ground end (GND1) in sequence, the control end of the first switch tube (Q3) is electrically connected with the control unit (7), the control end of the first switch tube (Q3) is connected in series with the first end of the first switch tube (Q3) through the second resistance (R42), the second end of the first switch tube (Q3) and the first voltage end (300) are connected with the input end of the first inductor (LF3) respectively, the output end of the first inductor (LF3) is electrically connected with the light source assembly (200). The first voltage stabilization unit (5) comprises a second diode (D13), a third diode (D14), a three-terminal voltage regulator (U4), an optical coupler (U1A), a third resistance (R38), a fourth resistance (R39), a fifth resistance (R40), a sixth resistance (R47), a seventh resistance (R47A), an eighth resistance (R48), a fifth capacitor (C18), a sixth capacitor (C29), a seventh capacitor (C30), an eighth capacitor (CE3).

6. The thyristor dimming device of the LED driving power supply according to any one of claims 1-5, wherein: The positive electrode of the second diode (D13) is electrically connected with the first end of the output end of the voltage conversion unit (1), the eighth capacitor (CE3) and the third resistance (R38) are connected in parallel between the negative electrode of the second diode (D13) and the first ground end (GND), the third diode (D14) and the three-terminal voltage regulator (U4) are connected in series between the negative electrode of the second diode (D13) and the first ground end (GND), the fourth resistance (R39) and the optical coupler (U1A) are connected in sequence between the negative electrode of the second diode (D13) and the negative electrode of the three-terminal voltage regulator (U4), the sixth resistance (R47), the seventh resistance (R47A) and the eighth resistance (R48) are connected in sequence between the first voltage end (300) and the first ground end (GND), the fifth resistance (R40) and the fifth capacitor (C18) are connected in sequence between the control end of the three-terminal voltage regulator (U4) and the negative electrode of the three-terminal voltage regulator (U4), the two ends of the sixth capacitor (C29) are electrically connected with the negative electrode of the three-terminal voltage regulator (U4) and the seventh resistance (R47A) respectively, the control end of the three-terminal voltage regulator (U4) is electrically connected with the connection point of the seventh resistance (R47A) and the eighth resistance (R48), the seventh capacitor (C30) is connected in parallel between the two ends of the eighth resistance (R48). ​ 7. The LED driving power supply's thyristor dimming device according to claim 6, wherein: The rectifier unit (61) includes a fourth diode (D15), the voltage distribution unit (62) includes a ninth resistor (R34), a tenth resistor (R41), a ninth capacitor (C11), the second switch unit (63) includes a second switch tube (Q2), a fifth diode (D11), an eleventh resistor (R35), a twelfth resistor (R50); The negative electrode of the fourth diode (D15) is electrically connected with the first end of the output end of the voltage conversion unit (1) and the positive electrode of the second diode (D13), the positive electrode of the fourth diode (D15) is electrically connected with the control unit (7) after being connected with the tenth resistor (R41) and the twelfth resistor (R50) in turn, the ninth resistor (R34) and the ninth capacitor (C11) are arranged in parallel between the positive electrode of the fourth diode (D15) and the first ground end (GND), the control end of the second switch tube (Q2) is electrically connected with the connection point of the tenth resistor (R41) and the twelfth resistor (R50), the fifth diode (D11) is connected in series between the control end of the second switch tube (Q2) and the first ground end (GND), the eleventh resistor (R35) is connected in series between the first end of the second switch tube (Q2) and the control unit (7), and the second end of the second switch tube (Q2) is connected with the first ground end (GND).

8. The thyristor dimming apparatus of the LED driving power supply according to claim 3 or 5, wherein: The second voltage stabilizing unit (8) includes a first triode (Q8), a sixth diode (ZD6), a thirteenth resistor (R60) and a tenth capacitor (C28); The control end of the first triode (Q8) is connected in series with the thirteenth resistor (R60) between the first voltage end (300) and the first ground end (GND), the sixth diode (ZD6) is connected in series between the control end of the first triode (Q8) and the first ground end (GND), the first end of the first triode (Q8) is electrically connected with the first voltage end (300), the tenth capacitor (C28) is connected in series between the second end of the first triode (Q8) and the first ground end (GND), and the second end of the first triode (Q8) is electrically connected with the control unit (7).

9. The LED driving power supply's thyristor dimming device according to claim 8, wherein: The overcurrent protection unit (10) includes a second triode (Q4), a third triode (Q7), a seventh diode (D19), a fourteenth resistor (R32), a fifteenth resistor (R43), a sixteenth resistor (R44), a seventeenth resistor (R57), an eighteenth resistor (R58), an eleventh capacitor (C26) and a twelfth capacitor (C27). The control end of the second triode (Q4) is connected with the second end of the first triode (Q8) through the eighteenth resistor (R58) and the seventeenth resistor (R57) in sequence, the two ends of the eighteenth resistor (R58) are connected with the sixteenth resistor (R44) and the seventh diode (D19) in sequence, the connecting point of the sixteenth resistor (R44) and the seventh diode (D19) is connected with the second ground end (GND1), the control end and the first end of the second triode (Q4) are connected with the first end of the third triode (Q7) and the control end of the third triode (Q7) respectively, the twelfth capacitor (C27) is connected between the control end and the second end of the second triode (Q4), the second end of the second triode (Q4) is connected with the first ground end (GND), the control end and the second end of the third triode (Q7) are connected with the eleventh capacitor (C26) and the fifteenth resistor (R43) in parallel in sequence, the fourteenth resistor (R32) is connected between the second end of the third triode (Q7) and the control unit (7), and the second end of the third triode (Q7) is connected with the first switch unit (3).

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