Dimming low-end acceleration startup method and circuit

Abstract

The present invention discloses a dimming low-end accelerated startup method and circuit, comprising the following steps: S1, turn on the switch; S2, increase the duty cycle of the dimming signal; S3, restore the dimming signal; including a rectifier bridge, a filter circuit is connected after the rectifier bridge, a control circuit is connected after the filter circuit, a freewheeling diode is connected after the control circuit, an output filter capacitor is connected after the freewheeling diode, a lamp string is connected after the output filter capacitor, and a detection module is connected between the output filter capacitor and the lamp string; by indirectly measuring the voltage value at point A to determine the voltage value of the lamp string, and then determining the charging value of the electrolytic capacitor, while ensuring fast charging startup, the voltage will not be overcharged, avoiding the flashing of the lamp, the circuit is simple, the batch control consistency is good, and the startup time of the lamp can be <0.5S at any dimming level.

Description

Technical Field

[0001] The present invention relates to the technical field of dimmer control, and particularly to a low-end dimming acceleration start method and circuit. Background Art

[0002] When a dimmable lamp is turned off after being dimmed to a certain brightness, due to the memory function, the brightness of the lamp at the next turn-on is the brightness set last time. However, since it is a high-PF circuit, relatively small input capacitors are used. To reduce the output current ripple and the light fluctuation of the LED lamp, relatively large output capacitors are used. At the low end of dimming, since the current in the circuit is small, it takes a longer time for the output capacitor to charge to the LED lamp string voltage, which may be as long as 2S to start. Generally, customers require that the start-up time of the lamp be <0.5S to obtain a better application experience. Therefore, improvements need to be made in the control method and circuit so that the start-up time of the lamp can be <0.5S at any dimming level.

[0003] For example, a "soft start control circuit for LED acceleration start" disclosed in a Chinese patent document, with the publication number: CN101984734B, discloses a dimming module, an acceleration module, and a logic control module, which can achieve acceleration start and anti-flicker. However, the circuit logic is complex, there are too many variables, and the control effect is poor. Summary of the Invention

[0004] Therefore, the present invention provides a low-end dimming acceleration start method and circuit, which makes the lamp return to the original dimming brightness before starting, and solves the problem that the lamp first lights up 100% and then returns to the original dimming brightness, resulting in a flicker of the finished lamp.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The low-end dimming acceleration start method includes the following steps:

[0007] S1. Turn on the switch;

[0008] S2. Increase the duty ratio of the dimming signal to increase the charging current;

[0009] S3. Restore the dimming signal. Restore the dimming signal to the original memorized state, so that the lamp finally reaches the original memorized dimming brightness after starting, avoiding the lamp brightness being too high and then being reduced and adjusted.

[0010] Preferably, in S3, when the voltage of the electrolytic capacitor reaches 60-85% of the lamp string voltage, the dimming signal is adjusted to be restored to the original memorized state. This enables the lamp to be quickly charged during the lighting process without exceeding the original memorized brightness, avoiding too large a charging current and preventing waste and adjustment actions.

[0011] Preferably, in S1, the time from turning on the switch to when the lamp current of the lamp string reaches 90% is set as the startup time, which is used to control the charging current and voltage changes during the lamp startup process.

[0012] Preferably, in S2, the duty ratio of the dimming signal is adjusted to the maximum within the startup time, enabling the lamp to charge quickly and reducing the charging time.

[0013] Preferably, it includes obtaining the electrolytic capacitor voltage based on the measured point voltage, avoiding the problem of difficult measurement of floating ground lamp strings, determining the voltage value of the lamp string by indirectly measuring the voltage value, and then determining the electrolytic capacitor charging value.

[0014] The circuit for accelerating startup at the low end of dimming includes a rectifier bridge, a filter circuit is connected after the rectifier bridge, a control circuit is connected after the filter circuit, a freewheeling diode is connected after the control circuit, an output filter capacitor is connected after the freewheeling diode for reducing the output current ripple; a lamp string is connected after the output filter capacitor, and a detection module is connected between the output filter capacitor and the lamp string. The filter circuit includes a filter inductor L21, the first end of the filter inductor L21 is connected to the first end of the filter capacitor C21, the second end of the filter inductor L21 is connected to the first end of the filter capacitor C22, the second ends of the filter capacitor C22 and the filter capacitor C21 are both grounded, and the second end of the filter inductor L21 is connected to the control circuit. The second end of the freewheeling diode is connected to the first end of an inductor L41, the second end of the inductor L41 is connected to the second end of the output filter capacitor, and when the internal power MOS of the constant current dimming control IC is turned off, the freewheeling diode can provide a current loop for the inductor.

[0015] Preferably, the control circuit includes a constant current dimming control IC, an IC power supply capacitor and a detection resistor are respectively connected after the constant current dimming control IC. The HV interface of the constant current dimming control IC is connected to the filter circuit, the VCC interface of the constant current dimming control IC is connected to the IC power supply capacitor, the CS terminal of the constant current dimming control IC is connected to the detection resistor, and the detection resistor is used to detect the peak current. When the threshold voltage is reached, the internal MOS of the constant current dimming control IC is turned off. The S interface and the NC interface of the constant current dimming control IC are connected to the first end of the freewheeling diode, and the GND terminals of the IC power supply capacitor, the detection resistor and the constant current dimming control IC are all grounded. The model of the constant current dimming control IC is BP2306X.

[0016] Preferably, a dummy load is also connected between the output filter capacitor and the lamp string. The first end of the output filter capacitor is connected to the first end of the dummy load, the second end of the output filter capacitor is connected to the second end of the dummy load, the first end of the dummy load is also connected to the first end of the lamp string, and the second end of the dummy load is also connected to the second end of the lamp string, which is used to provide output open circuit protection detection.

[0017] Preferably, the detection module includes a voltage-dividing resistor RS32. After the voltage-dividing resistor RS32, there are respectively connected a voltage-dividing resistor RS31, a capacitor C31, and a wireless control module US32. The wireless control module US32 can be 2.4G, BLE, ZIGBEE, etc., and can adjust the duty cycle of the PWM signal of the DIM pin through wireless control to achieve the purpose of dimming. The first end of the voltage-dividing resistor RS32 is connected to the second end of the output filter capacitor. The second end of the voltage-dividing resistor RS32 is connected to the first end of the voltage-dividing resistor RS31. The first end of the voltage-dividing resistor RS31 is also connected to the first end of the capacitor C31. The second end of the voltage-dividing resistor RS31 and the second end of the capacitor C31 are both grounded. The second end of the voltage-dividing resistor RS32 is also connected to the ADC interface of the wireless control module US32. The GND interface of the wireless control module US32 is grounded. There is a measurement point A on the connection line between the ADC interface of the wireless control module US32 and the second end of the voltage-dividing resistor RS32. The model of the wireless control module US32 is BWZBM02.

[0018] The present invention has the following advantages:

[0019] (1) By indirectly measuring the voltage value at point A to determine the voltage value of the lamp string and then determining the charging value of the electrolytic capacitor, this method ensures fast charging startup without overcharging the voltage, avoiding lamp flickering. (2) The circuit is simple and has good batch control consistency. (3) The startup time of the lamp can be <0.5S at any dimming level. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only exemplary, and for those of ordinary skill in the art, other implementation drawings can be obtained by extending based on the provided drawings without creative labor.

[0021] Figure 1 It is a method step diagram of the present invention.

[0022] Figure 2 It is a circuit structure schematic diagram of the present invention.

[0023] Figure 3 It is a dimming signal change diagram during accelerated startup of the present invention.

[0024] In the figure:

[0025] BS11 - Rectifier bridge; L21 - Filter inductor; C21 - Filter capacitor; C22 - Filter capacitor; US31 - Constant current dimming control IC; CS61 - IC power supply capacitor; RS41 - Detection resistor; DS41 - Freewheeling diode; CD41 - Output filter capacitor; RS51 - Fake load; D1D2…DN - Lamp string; RS31 - Voltage dividing resistor; RS32 - Voltage dividing resistor; US31 - Group - free control module. Detailed implementation mode

[0026] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] As Figures 1-3 shown, in a preferred embodiment, the present invention discloses a low - end acceleration start - up method for dimming, including the following steps:

[0028] S1. Turn on the switch;

[0029] S2. Increase the duty cycle of the dimming signal to increase the charging current;

[0030] S3. Restore the dimming signal. Restore the dimming signal to its original memorized state, so that the lamp finally reaches the original memorized dimming brightness after startup, avoiding the lamp brightness being too high and then being reduced and adjusted.

[0031] In S3, it includes that when the voltage of the electrolytic capacitor reaches 60 - 85% of the lamp string voltage, adjust the dimming signal to restore to its original memorized state. This enables the lamp to be quickly charged during the light - emitting process without exceeding the original memorized brightness, avoiding excessive charging current and preventing waste and adjustment actions. When in use, change the lamp startup signal according to the lamp startup process, and change the time when the startup current is first large and then small to avoid lamp flickering.

[0032] In S1, it includes setting the time from turning on the switch to the lamp string reaching 90% of the lamp current as the startup time. This is used to control the charging current and voltage changes during the lamp startup process. When in use, adjust the startup time according to the startup rate of the lamp and the desired final brightness.

[0033] In S2, adjust the duty cycle of the dimming signal to the maximum within the startup time. This enables the lamp to be quickly charged and reduces the charging time. When in use, quickly make the lamp reach the target brightness by setting the maximum duty cycle of the dimming signal.

[0034] It includes obtaining the electrolytic capacitor voltage based on the measured point voltage. This avoids the problem of difficult measurement of floating ground lamp strings. By indirectly measuring the voltage value to determine the voltage value of the lamp string and then determining the electrolytic capacitor charging value. When in use, after indirectly obtaining the lamp string voltage, it is possible to better control the lamp string current and avoid the insecurity caused by additional circuits.

[0035] A circuit for accelerating startup at the low end of dimming includes a rectifier bridge. After the rectifier bridge, there is a connected filter circuit. After the filter circuit, there is a connected control circuit. After the control circuit, there is a connected freewheeling diode. After the freewheeling diode, there is a connected output filter capacitor for reducing the output current ripple. After the output filter capacitor, there is a connected lamp string, and between the output filter capacitor and the lamp string, there is a connected detection module. The filter circuit includes a filter inductor L21. The first end of the filter inductor L21 is connected to the first end of the filter capacitor C21. The second end of the filter inductor L21 is connected to the first end of the filter capacitor C22. The second ends of the filter capacitor C22 and the filter capacitor C21 are both grounded. The second end of the filter inductor L21 is connected to the control circuit. The second end of the freewheeling diode is connected to the first end of an inductor L41. The second end of the inductor L41 is connected to the second end of the output filter capacitor. When the internal power MOS of the constant current dimming control IC is turned off, the freewheeling diode can provide a current path for the inductor. When in use, the alternating current is changed into a starting current through the starting circuit.

[0036] The control circuit includes a constant current dimming control IC. After the constant current dimming control IC, there are respectively connected an IC power supply capacitor and a detection resistor. The HV interface of the constant current dimming control IC is connected to the filter circuit. The VCC interface of the constant current dimming control IC is connected to the IC power supply capacitor. The CS terminal of the constant current dimming control IC is connected to the detection resistor. The detection resistor is used to detect the peak current. When the threshold voltage is reached, the internal MOS of the constant current dimming control IC is turned off. The S interface and the NC interface of the constant current dimming control IC are connected to the first end of the freewheeling diode. The GND terminals of the IC power supply capacitor, the detection resistor, and the constant current dimming control IC are all grounded. The model of the constant current dimming control IC is BP2306X. When in use, the starting current is controlled through the control circuit.

[0037] There is also a connected dummy load between the output filter capacitor and the lamp string. The first end of the output filter capacitor is connected to the first end of the dummy load. The second end of the output filter capacitor is connected to the second end of the dummy load. The first end of the dummy load is also connected to the first end of the lamp string. The second end of the dummy load is also connected to the second end of the lamp string, which is used to provide output open circuit protection detection. When in use, the safety is improved through the dummy load. When the lamp is open, protection is carried out to avoid all being burned out.

[0038] The detection module includes a voltage-dividing resistor RS32. After the voltage-dividing resistor RS32, there are respectively connected a voltage-dividing resistor RS31, a capacitor C31, and a wireless control module US32. The wireless control module US32 can be 2.4G, BLE, ZIGBEE, etc. It can adjust the duty cycle of the PWM signal of the DIM pin through wireless control to achieve the purpose of dimming. The first end of the voltage-dividing resistor RS32 is connected to the second end of the output filter capacitor. The second end of the voltage-dividing resistor RS32 is connected to the first end of the voltage-dividing resistor RS31. The first end of the voltage-dividing resistor RS31 is also connected to the first end of the capacitor C31. The second end of the voltage-dividing resistor RS31 and the second end of the capacitor C31 are both grounded. The second end of the voltage-dividing resistor RS32 is also connected to the ADC interface of the wireless control module US32. The GND interface of the wireless control module US32 is grounded. There is a measurement point A on the connection line between the ADC interface of the wireless control module US32 and the second end of the voltage-dividing resistor RS32. There is a measurement point DCBUS on the connection line between the first end of the freewheeling diode and the first end of the output filter capacitor. The model of the wireless control module US32 is BWZBM02. During use, the detection module is used to substitute and detect the voltage of the lamp string.

[0039] The voltage at point A corresponds to the voltage value of the LED lamp string. Read the voltage value at point A, input it through the PIN1 pin of US32, and obtain the voltage value at point A through analog-to-digital conversion. Before the voltage value at point A reaches the threshold VA set inside US32, the PIN6 of US32 outputs a dimming signal with a 100% duty cycle to accelerate the charging of the electrolytic capacitor CD41. When the threshold is reached, the PWM signal resumes the dimming duty cycle of the original memory.

[0040] Determination of the threshold VA of the voltage at point A:

[0041]

[0042] In the formula:

[0043] V DCBUS : DCBUS voltage;

[0044] RS31, RS32: Resistance values of the voltage-dividing resistors;

[0045] VD1D2…DN: Voltage of the LED lamp string;

[0046] VA: Voltage value at point A in the figure;

[0047] ∝: Lamp string voltage coefficient, generally set to 0.6 - 0.85.

[0048] The DCBUS voltage, the resistance values of the voltage-dividing resistors RS31 and RS32, the voltage of the LED lamp string VD1D2…DN, and ∝ are all known, so the voltage at point A can be determined.

[0049] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A circuit for low-end accelerated start-up of dimming, characterized in that, It includes a rectifier bridge, followed by a filter circuit, then a control circuit, then a freewheeling diode, then an output filter capacitor, and then a lamp string. A detection module is connected between the output filter capacitor and the lamp string; The detection module includes a voltage-dividing resistor RS32, which is respectively connected to a voltage-dividing resistor RS31, a capacitor C31, and a non-group control module US32; A measurement point A is provided on the connection line between the ADC interface of the non-group control module US32 and the second end of the voltage-dividing resistor RS32, and a measurement point DCBUS is provided on the connection line between the first end of the freewheeling diode and the first end of the output filter capacitor; The control circuit includes a constant-current dimming control IC. The HV interface of the constant-current dimming control IC is connected to the filter circuit, the VCC interface is connected to an IC power supply capacitor, the CS terminal is connected to a detection resistor for detecting the peak current. When the threshold voltage is reached, the internal MOS of the constant-current dimming control IC turns off.

2. The dimming low-end acceleration start-up circuit according to claim 1, wherein An IC power supply capacitor and a detection resistor are respectively connected after the constant-current dimming control IC; 3. The circuit for low-end accelerated start-up of dimming according to claim 1, characterized in that, The S interface and the NC interface of the constant-current dimming control IC are connected to the first end of the freewheeling diode, and the GND terminals of the IC power supply capacitor, the detection resistor, and the constant-current dimming control IC are all grounded; 4. The dimming low-end acceleration start-up circuit according to claim 2, characterized in that, A dummy load is also connected between the output filter capacitor and the lamp string; 5. The dimming low-end acceleration start-up circuit according to claim 3, characterized in that, The first end of the output filter capacitor is connected to the first end of the dummy load, the second end of the output filter capacitor is connected to the second end of the dummy load, the first end of the dummy load is also connected to the first end of the lamp string, and the second end of the dummy load is also connected to the second end of the lamp string; 6. The dimming low-end acceleration start-up circuit according to claim 5, characterized in that, The first end of the voltage-dividing resistor RS32 is connected to the second end of the output filter capacitor, the second end of the voltage-dividing resistor RS32 is connected to the first end of the voltage-dividing resistor RS31, and the first end of the voltage-dividing resistor RS31 is also connected to the first end of the capacitor C31; 7. The dimming low-end acceleration start-up circuit according to claim 6, characterized in that, The second ends of the voltage-dividing resistor RS31 and the capacitor C31 are both grounded; the second end of the voltage-dividing resistor RS32 is also connected to the ADC interface of the non-group control module US32, and the GND interface of the non-group control module US32 is grounded.

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