Conduction angle generating circuit and LED drive circuit

Abstract

The utility model provides a conduction angle generating circuit and an LED drive circuit, and the conduction angle generating circuit comprises a register unit which stores the actual conduction angles of a silicon controlled rectifier dimmer in continuous N periods before the current period, N being an integer greater than 1; the arithmetic unit is used for calculating the average value of the actual conduction angles in the N periods and solving the difference value between the average value and the final conduction angle of the previous period; and the fuzzy unit generates a final conduction angle of the current period according to the difference value and a preset difference value range. According to the utility model, the actual conduction angles of the silicon controlled rectifier dimmer in a plurality of adjacent periods in each period are processed to obtain the final conduction angle, so that the conduction angle fluctuation between the adjacent periods is reduced, the fluctuation amplitude of the LED reference current is reduced, and the LED lamp shaking is avoided.

Description

Technical Field

[0001] This utility model belongs to the field of dimming, specifically relating to a conduction angle generating circuit and an LED driving circuit. Background Technology

[0002] A dimming circuit equipped with a silicon controlled rectifier (SCR) dimmer achieves dimming by adjusting the conduction angle of each half-wave of the alternating current to change the effective value of the input voltage. However, due to the inherent characteristics of the SCR dimmer, such as... Figure 1 As shown, the thyristor dimmer exhibits a large and small wave problem when the positive and negative half-cycles of the AC current are tangent, resulting in one conduction angle being slightly larger and the other slightly smaller in adjacent cycles, which in turn causes LED current fluctuations and LED flickering.

[0003] Solutions proposed by existing technologies, such as Figure 2 As shown, capacitor C1 and a ripple reduction chip are added. Capacitor C1 supplies power to the LED when Vbus is less than the LED's on-state voltage drop. The ripple reduction chip smooths out the LED current ripple, thereby preventing LED current fluctuations and LED flickering.

[0004] However, adding capacitors and ripple-reducing chips will inevitably increase costs. Utility Model Content

[0005] To address the high cost of existing solutions, this invention proposes a conduction angle generating circuit and an LED driving circuit. The conduction angle generating circuit includes:

[0006] The register unit stores the actual conduction angles of the SCR dimmer for the N consecutive cycles preceding the current cycle, where N is an integer greater than 1.

[0007] The arithmetic unit calculates the average value of the actual conduction angle over N cycles and obtains the difference between the average value and the final conduction angle of the previous cycle.

[0008] The fuzzy unit generates the final conduction angle for the current cycle based on the difference and a preset difference range.

[0009] Furthermore, when the difference is within a preset difference range, the final conduction angle of the previous cycle is used as the final conduction angle of the current cycle;

[0010] When the difference exceeds the preset difference range, the average value of the actual conduction angles of N cycles is taken as the final conduction angle of the current cycle.

[0011] Furthermore, it also includes a detection unit that detects the conduction angle of the thyristor dimmer in each cycle as the actual conduction angle.

[0012] Preferably, the register unit includes N registers, which store the actual conduction angle for N cycles, and one of the registers updates the actual conduction angle for the current cycle.

[0013] Preferably, the fuzzy unit includes a comparator and a register. The comparator determines whether the difference exceeds a preset difference range by comparison. The register stores the final conduction angle of the previous cycle, and updates the storage of the final conduction angle of the current cycle when the difference exceeds the preset difference range.

[0014] Preferably, the detection unit includes a counter that counts from the moment the input voltage crosses zero to the moment the thyristor dimmer turns on, in order to obtain the actual conduction angle.

[0015] Preferably, the arithmetic unit includes an adder, a divider, and a subtractor. The adder sums the actual conduction angles of N cycles, the divider averages the summation results, and the subtractor calculates the difference between the average value and the final conduction angle of the previous cycle.

[0016] An LED driving circuit includes a silicon controlled rectifier (SCR) dimmer and the aforementioned conduction angle generation circuit to determine the final conduction angle of the current cycle.

[0017] Furthermore, the LED driving circuit determines the reference current of the LED based on the final conduction angle.

[0018] The proposed conduction angle generation circuit in this scheme averages the actual conduction angles over multiple adjacent cycles, and then processes the average value to further avoid instability. This achieves stability in both the final conduction angle and the current reference. Attached Figure Description

[0019] Figure 1 The conduction angle of the thyristor dimmer over multiple consecutive cycles;

[0020] Figure 2 This is existing technology;

[0021] Figure 3 This is a structural block diagram of the conduction angle generation circuit proposed in this utility model;

[0022] Figure 4 The digital circuit structure for generating the conduction angle. Detailed Implementation

[0023] To facilitate understanding of this utility model, a more comprehensive description will be given below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of this utility model. However, this utility model can be implemented in various forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0024] As described in the background section, existing technologies address LED flickering by adding capacitors and ripple-reducing chips to the LED driver circuit. However, this approach increases production costs and chip space requirements.

[0025] Therefore, this utility model proposes a conduction angle generating circuit, comprising:

[0026] The detection unit detects the conduction angle of the SCR dimmer in each cycle and records this conduction angle as the actual conduction angle of the SCR dimmer.

[0027] The register cell stores the actual conduction angles for the N consecutive cycles preceding the current cycle, where N is an integer greater than 1.

[0028] The arithmetic unit calculates the average value of the actual conduction angle over N cycles and obtains the difference between the average value and the final conduction angle of the previous cycle.

[0029] The fuzzy unit generates the final conduction angle for the current cycle based on the difference and a preset difference range. The LED driver circuit determines the reference current of the LED based on the final conduction angle. Specifically, when the difference is within the preset difference range, the final conduction angle of the previous cycle is set as the final conduction angle of the current cycle; when the difference exceeds the preset difference range, the average value of the actual conduction angles within the N cycles is set as the final conduction angle of the current cycle.

[0030] Therefore, this solution proposes to process the actual conduction angle of the thyristor dimmer in each cycle to obtain the final conduction angle, thereby reducing the conduction angle fluctuation between adjacent cycles, which in turn reduces the fluctuation amplitude of the LED reference current and avoids LED flickering.

[0031] The following describes the conduction angle generation circuit proposed in this solution in further detail with reference to specific embodiments.

[0032] Preferred, such as Figure 1 and Figure 3 As shown, assuming the current cycle is the Mth cycle, the final conduction angle of the Mth cycle is obtained based on the actual conduction angles of the previous 3 cycles. The conduction angle (actual conduction angle) of the M-1th cycle is detected and obtained within the (M-1)th cycle as θ. M-1 , and θ M-1 It is stored in the register cell. Meanwhile, the final conduction angle of the (M-1)th cycle is α.M-1 α M-1 Stored in the fuzzy unit. The actual conduction angle of the (M-2)th cycle is obtained by detection within the (M-2)th cycle. M-2 θ M-2 Stored in the register unit. The actual conduction angle of the (M-3)th cycle is detected and obtained as θ. M-3 θ M-3 Stored in the register unit. Within the current cycle, the arithmetic unit calculates the average value of the actual conduction angle of the previous three cycles. And calculate the difference between the average value and the final conduction angle of the previous cycle. if If the difference exceeds the preset range (Φ1, Φ2), then let As the final conduction angle of the current cycle, within the current cycle according to Determine the reference current for the LED; if If the difference is within the preset range (Φ1, Φ2), then the final conduction angle α of the previous cycle is set to... M-1 As the final conduction angle of the current cycle, within the current cycle, according to α M-1 Determine the reference current for the LED.

[0033] It should be noted that the actual conduction angle θ will also be detected during the current cycle. M The register will store θ M The updated value is stored in the register unit, and the final conduction angle of the current cycle is also stored in the fuzzy unit. This allows the actual conduction angle and the final conduction angle of the current cycle to be read and retrieved when obtaining the final conduction angle of the next cycle. The above embodiment uses three consecutive cycles as an example, but in practice, any number of consecutive cycles can be selected.

[0034] It should also be noted that when M is 1, i.e., when the current cycle is the first cycle, the final conduction angle can still be generated according to the conduction angle generation circuit described above. Specifically, the actual conduction angle of the first three cycles can be considered as 0, so according to the processing of the conduction angle generation circuit described above, the final conduction angle of the current cycle can be obtained as 0. In each subsequent cycle, the final conduction angle is obtained according to the above processing. Similarly, when M is 2 or 3, the final conduction angle can also be generated according to the conduction angle generation circuit described above.

[0035] Preferably, digital circuits offer advantages such as strong anti-interference capability, high stability, ease of integration, and convenient storage and transmission. The aforementioned conduction angle generation circuit is specifically implemented using digital circuitry, such as... Figure 4The conduction angle generation circuit shown is implemented using digital circuitry. Specifically, the detection unit includes a counter. Taking a leading-edge phase-cut dimmer as an example, the counter starts counting at the zero-crossing point of the input voltage until the turn-on time of the SCR dimmer. After processing the counting result, the conduction angle (actual conduction angle) of the SCR dimmer can be obtained. The register unit includes register 1, register 2, and register 3. Register 1 stores θ. M-1 Register 2 stores θ M-2 Register 3 stores θ M-3 The arithmetic unit can be implemented using adders, dividers, and subtractors; the adder sums θ. M-3 +θ M-2 +θ M-1 The average value of the divider output Subtractor output difference The fuzzy unit is implemented using register 4 and a comparator. Register 4 is used to store the final conduction angle α of the previous cycle. M-1 The comparator compares the difference. If the difference is within the preset difference range (Φ1, Φ2), register 4 outputs α. M-1 As the final conduction angle of the current cycle, if the difference is outside the preset difference range, register 4 updates the stored average value. Output the average value This serves as the final conduction angle for the current cycle. Simultaneously, the counter acquires the conduction angle θ for the current cycle. M Register 3 will update the storage of θ M Thus, in the next cycle, the conduction angle generation circuit can repeat the above operation to obtain the final conduction angle of the next cycle.

[0036] Obviously, when the conduction angle generation circuit is implemented using digital circuitry, the signals processed by the registers, arithmetic logic unit (ALU), and comparators are all binary codes. Furthermore, the specific configuration of counters, registers, adders, dividers, comparators, etc., to implement the conduction angle generation circuit is standard practice for those skilled in the art and will not be elaborated upon here.

[0037] In summary, the conduction angle generation circuit proposed in this solution further avoids instability by averaging the actual conduction angles of multiple adjacent cycles and then processing the average value. This achieves stability of both the final conduction angle and the current reference.

[0038] This utility model also proposes an LED driving circuit, which includes the conduction angle generation circuit mentioned above, and determines the current reference based on the final conduction angle obtained by the conduction angle generation circuit.

[0039] It should be noted that the specific implementation and corresponding illustrations provided are merely one way of describing the implementation method of this utility model, and are not intended to limit the specific structure of the implementation scheme of this utility model. Various changes or modifications can be made to these implementation methods without departing from the principles and essence of this utility model, but all such changes and modifications fall within the protection scope of this utility model.

[0040] Although the embodiments are described and illustrated separately above, some common technologies are involved. Those skilled in the art can replace and integrate them between the embodiments. If there is any content not explicitly described in one embodiment, then another embodiment that is described can be referred to.

[0041] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A conduction angle generating circuit characterized by comprising: The application relates to an LED driving circuit, comprising: a register unit, comprising N registers, wherein the N registers respectively store actual conduction angles of a triac dimmer in N continuous periods before a current period, and N is an integer greater than 1; an operation unit, which calculates an average value of the actual conduction angles in the N periods and obtains a difference value between the average value and a final conduction angle in a previous period; a fuzzy unit, comprising a comparator and a register, wherein the comparator compares whether the difference value exceeds a preset difference value range, and when the difference value exceeds the preset difference value range, the register in the fuzzy unit updates the average value of the actual conduction angles in the N periods as the final conduction angle in the current period according to an output of the comparator.

2. The conduction angle generating circuit of claim 1, wherein When the difference value is within the preset difference value range, the register in the fuzzy unit retains the original stored final conduction angle in the previous period as the final conduction angle in the current period according to the output of the comparator.

3. The conduction angle generating circuit of claim 1, wherein The LED driving circuit further comprises a detection unit, which detects a conduction angle of the triac dimmer as the actual conduction angle in each period.

4. The conduction angle generating circuit of claim 1, wherein After the final conduction angle in the current period is determined, one register in the register unit updates the actual conduction angle in the current period.

5. The conduction angle generating circuit of claim 3, wherein The detection unit comprises a counter, which starts counting from a zero-crossing time of an input voltage to a conduction time of the triac dimmer to obtain the actual conduction angle.

6. The conduction angle generating circuit of claim 1, wherein The operation unit comprises an adder, a divider and a subtractor, wherein the adder sums the actual conduction angles in the N periods, the divider averages the sum, and the subtractor obtains the difference value between the average value and the final conduction angle in the previous period.

7. An LED driving circuit comprising a thyristor dimmer, characterized in that The LED driving circuit further comprises a conduction angle generation circuit according to any one of claims 1-6 to determine the final conduction angle in the current period.

8. The LED driving circuit of claim 7, wherein, The LED driving circuit determines a reference current of the LED according to the final conduction angle.

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