Silicon controlled rectifier dimming detection circuit

Abstract

The utility model relates to the technical field of LED control circuits, in particular to a silicon controlled rectifier dimming detection circuit, which comprises a silicon controlled rectifier dimmer, and a diode D1, a diode D2, an AC-DC constant voltage control module, a transformer T1, a diode D3, a diode D4, a diode D5 and a DC-DC constant current control module which are connected with the silicon controlled rectifier dimmer. The resistor R1, the resistor R2, the resistor R3 and the Zener diode ZD1 are connected with the diode D1, the resistor R4, the capacitor C1, the resistor R5 and one end of the MOS tube Q1 are connected between the resistor R3 and the Zener diode ZD1, the optocoupler U1 is connected with the other end of the MOS tube Q1, the MOS tube Q2 is connected with the other end of the optocoupler U1, the three groups of RC filters are connected with the other end of the MOS tube Q2, and the single chip microcomputer U2 is connected with the three groups of RC filters. The other end of the single-chip microcomputer U2 is connected with the DC-DC constant current control module and the LED lamp. According to the silicon controlled rectifier dimming detection circuit, the signal is converted into the direct current signal to control the output constant current dimming circuit, so that the stable and flexible control of silicon controlled rectifier dimming is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of signal digital-analog conversion, in particular to a thyristor dimming detection circuit. Background Art

[0002] Thyristor dimming for resistive loads offers a simple circuit design and widespread market application. However, because LED drivers use capacitive loads, thyristor dimming can be prone to dithering, affecting output. Thyristor dimming typically operates at 50Hz or 60Hz, resulting in a slow flicker that can affect user experience and cause visual fatigue. Therefore, a thyristor dimming detection circuit is urgently needed to address these issues. Utility Model Content

[0003] The purpose of the utility model is to provide a thyristor dimming detection circuit to solve the technical problems of existing thyristor dimming control LED driver products, such as dimming flicker, light jitter due to input mains fluctuations, and small dimming depth.

[0004] The utility model provides a thyristor dimming detection circuit, comprising a thyristor dimmer, a diode D1 and a diode D2 connected thereto, an AC-DC constant voltage control module connected to the diode D2, a transformer T1 connected to the AC-DC constant voltage control module, a diode D3, a diode D4 and a diode D5 connected to the transformer T1, and a DC-DC constant current control module connected to the transformer T1;

[0005] It also includes a resistor R1, a resistor R2, a resistor R3 and a Zener diode ZD1 connected to the diode D1, a resistor R4 connected between the resistor R3 and the Zener diode ZD1, a capacitor C1, a resistor R5 and one end of the MOS transistor Q1, an optocoupler U1 connected to the other end of the MOS transistor Q1, a MOS transistor Q2 connected to the other end of the optocoupler U1, three groups of RC filters connected to the other end of the MOS transistor Q2, and a single-chip microcomputer U2 connected to the three groups of RC filters. The other end of the single-chip microcomputer U2 is connected to the DC-DC constant current control module and the LED lamp.

[0006] Preferably, one end of the diode D3 is connected to a capacitor C5 , one end of the diode D4 is connected to a capacitor C7 , one end of the diode D5 is connected to a capacitor C6 , and the diode D3 is connected to one end of the optocoupler U1 via a resistor R6 .

[0007] Preferably, the three groups of RC filters are respectively a resistor R11 and a capacitor C2; a resistor R12 and a capacitor C3; and a resistor R13 and a capacitor C4.

[0008] Compared with the prior art, the beneficial effects of the present invention are:

[0009] This new thyristor dimming detection circuit uses a thyristor to adjust the input mains voltage to control the dimming angle, which is the duration of the dimming operation. Through current limiting and voltage stabilization, a PWM signal with the mains voltage as the period and the duty cycle as the on-time is generated. This signal is then transmitted to the secondary circuit in the same proportion. After shaping and amplification, it is then filtered by RC and converted into a voltage signal. A single-chip microcontroller analyzes this voltage signal to determine whether a dimmer is connected and the duration of the dimming operation. It then outputs a signal to control the constant current circuit of the LED lamp, thereby controlling the LED current. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0011] Figure 1 The utility model is a circuit diagram of a thyristor dimming detection circuit. DETAILED DESCRIPTION

[0012] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0013] like Figure 1 As shown, a thyristor dimming detection circuit of the present invention includes a thyristor dimmer, a diode D1 and a diode D2 connected thereto, an AC-DC constant voltage control module connected to the diode D2, a transformer T1 connected to the AC-DC constant voltage control module, a diode D3, a diode D4 and a diode D5 connected to the transformer T1, and a DC-DC constant current control module connected to the transformer T1;

[0014] The system also includes resistors R1, R2, R3, and a Zener diode ZD1 connected to diode D1; resistor R4 connected between resistor R3 and Zener diode ZD1; capacitor C1; resistor R5; one end of a MOS transistor Q1; an optocoupler U1 connected to the other end of MOS transistor Q1; a MOS transistor Q2 connected to the other end of optocoupler U1; three sets of RC filters connected to the other end of MOS transistor Q2; and a single-chip microcomputer U2 connected to the three sets of RC filters. The other end of single-chip microcomputer U2 is connected to the DC-DC constant current control module and the LED lamp. One end of diode D3 is connected to capacitor C5; one end of diode D4 is connected to capacitor C7; one end of diode D5 is connected to capacitor C6; and diode D3 is connected to one end of optocoupler U1 via resistor R6. The three sets of RC filters are resistor R11 and capacitor C2; resistor R12 and capacitor C3; and resistor R13 and capacitor C4.

[0015] The utility model discloses a thyristor dimmer in a thyristor dimming detection circuit, which converts the thyristor dimming input into a time signal. The thyristor dimming angle corresponds to the dimming maintenance time. The thyristor dimming angle is converted into a PWM signal with the mains power period as the conduction time as the duty cycle and the period as the mains power period. The PWM signal is transmitted to the secondary side through optical coupling isolation. The PWM signal is filtered by RC. Different duty cycles give different voltage signals. That is, the dimming angle is converted into a voltage signal. After being processed by the MCU, the current value of driving the LED is output to realize LED dimming.

[0016] This utility model features a thyristor dimming detection circuit. The thyristor adjusts the input mains power to control the dimming angle, specifically the duration of dimming. Current limiting and voltage stabilization generate a PWM signal with the mains power as the period and the duty cycle as the on-time. This signal is then transmitted to the secondary circuit in the same proportion, shaped and amplified, and then filtered by RC to convert it into a voltage signal. A single-chip microcomputer analyzes this voltage signal to determine whether a dimmer is connected and the duration of dimming. The microcontroller then outputs a signal to control the constant current circuit of the LED lamp, thereby controlling the LED current.

[0017] The PWM dimming working principle of the thyristor dimming detection circuit is:

[0018] The thyristor dimmer input waveform is rectified, current limited by resistors R1, R2, and R3, and stabilized by Zener diode ZD1. This results in a duty cycle with varying durations for thyristor dimming, with the period being the mains cycle. The dimmer is brightest when the duty cycle is maximum, and dimmest when the duty cycle is minimum. These varying duty cycle signals are amplified by MOS transistor Q1 and driven by optocoupler U1 for isolation, resulting in the output of a uniform duty cycle signal from optocoupler U1.

[0019] The signal is shaped and amplified by MOS tube Q2 and converted to a DC voltage V through three sets of RC filters. The RC filters effectively filter out the slight jitter caused by the dimmer, resulting in a stable voltage. Different duty cycles of the dimmer input are converted into different voltages V.

[0020] The voltage V signal is detected and judged by the single-chip microcomputer U2, and the corresponding different signals are output to control the constant current circuit, output the corresponding LED current, and finally control the LED brightness.

[0021] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A thyristor dimming detection circuit, characterized by: It includes a thyristor dimmer, diodes D1 and D2 connected thereto, an AC-DC constant voltage control module connected to diode D2, a transformer T1 connected to the AC-DC constant voltage control module, diodes D3, D4 and D5 connected to transformer T1, and a DC-DC constant current control module connected to transformer T1; It also includes a resistor R1, a resistor R2, a resistor R3 and a Zener diode ZD1 connected to the diode D1, a resistor R4 connected between the resistor R3 and the Zener diode ZD1, a capacitor C1, a resistor R5 and one end of the MOS transistor Q1, an optocoupler U1 connected to the other end of the MOS transistor Q1, a MOS transistor Q2 connected to the other end of the optocoupler U1, three groups of RC filters connected to the other end of the MOS transistor Q2, and a single-chip microcomputer U2 connected to the three groups of RC filters. The other end of the single-chip microcomputer U2 is connected to the DC-DC constant current control module and the LED lamp.

2. The thyristor dimming detection circuit according to claim 1, characterized in that: One end of the diode D3 is connected to the capacitor C5 , one end of the diode D4 is connected to the capacitor C7 , one end of the diode D5 is connected to the capacitor C6 , and the diode D3 is connected to one end of the optocoupler U1 via the resistor R6 .

3. The thyristor dimming detection circuit according to claim 1, characterized in that: The three groups of RC filters are respectively a resistor R11 and a capacitor C2; a resistor R12 and a capacitor C3; and a resistor R13 and a capacitor C4.

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