A thyristor detection and maintenance circuit

Abstract

The utility model relates to the field of lighting electronic circuit provides a thyristor detection and maintenance circuit, including diode rectifier circuit, maintenance circuit, phase detection circuit, signal amplification circuit, signal filter circuit and signal output circuit, diode rectifier circuit's input end connects through the thyristor voltage regulation alternating voltage input, maintenance circuit with diode rectifier circuit's output end is connected, phase detection circuit with diode rectifier circuit's output end is connected, signal amplification circuit's input end connects phase detection circuit's output end, and output end connects signal filter circuit's input end, signal filter circuit's output end connects signal output circuit's input end, signal output circuit's output end to LED drive circuit output drive signal, the utility model discloses to the thyristor output carries out phase detection, and then controls LED drive, guarantees LED output stability.

Description

Technical Field

[0001] This utility model relates to the field of lighting electronic circuits, and more specifically, to a silicon controlled rectifier (SCR) detection and maintenance circuit. Background Technology

[0002] In LED lighting, SCR dimming power supplies greatly reduce the hassle of rewiring compared to other dimming products. The brightness and switching of lights can be controlled by simply replacing the existing wall switch with a SCR dimmer. Therefore, SCR LED lighting has a wide range of applications.

[0003] Traditional SCR circuits typically place the SCR at the input line, and after rectification, the LED driver circuit controls the output of the LED. To maintain the SCR's operation, a sustaining circuit is needed to provide sustaining current. However, in controlling the LED driver circuit, the voltage phase after adjustment by the SCR dimmer can be different, causing abnormal fluctuations in the LED output and unstable LED operation. In traditional solutions, the LED driver circuit control signal is directly output from the main control chip. To eliminate the influence of voltage phase, an RC filter circuit needs to be added to the input side, and a large number of resistors need to be added at the input to smooth the dimmer signal, thus increasing the possibility of product malfunctions. Utility Model Content

[0004] The problem solved by this invention is how to provide a thyristor detection and maintenance circuit that can detect the phase of the thyristor output, thereby controlling the LED driver and ensuring stable LED output.

[0005] To address the aforementioned problems, this utility model provides a thyristor detection and sustaining circuit, comprising: a diode rectifier circuit, a sustaining circuit, a phase detection circuit, a signal amplification circuit, a signal filtering circuit, and a signal output circuit. The input terminal of the diode rectifier circuit is connected to an AC voltage input regulated by the thyristor. The sustaining circuit is connected to the output terminal of the diode rectifier circuit to provide a sustaining current for the thyristor. The phase detection circuit is connected to the output terminal of the diode rectifier circuit to output a corresponding detection signal based on the detected voltage phase. The input terminal of the signal amplification circuit is connected to the output terminal of the phase detection circuit, and its output terminal is connected to the input terminal of the signal filtering circuit. The output terminal of the signal filtering circuit is connected to the input terminal of the signal output circuit. The output terminal of the signal output circuit outputs a driving signal to an LED driving circuit.

[0006] Furthermore, the phase detection circuit includes a first voltage divider resistor group, a first three-terminal regulator, and a first optocoupler. The input terminal of the first voltage divider resistor group is connected to the output terminal of the diode rectifier circuit, the voltage divider output terminal is connected to the reference terminal of the first three-terminal regulator, the anode of the first three-terminal regulator is grounded, and the cathode is connected to the power supply via the input side of the first optocoupler.

[0007] Furthermore, the signal amplification circuit includes an inverting isolation circuit and an operational amplifier circuit connected in sequence.

[0008] Furthermore, the reverse isolation circuit includes a first MOS transistor, the gate and source of which are respectively connected to the two ends of the output side of the first optocoupler, and the drain of the first MOS transistor is connected to a 5V power supply.

[0009] Furthermore, the operational amplifier circuit includes a first operational amplifier and a first feedback resistor. The non-inverting input terminal of the first operational amplifier is connected to the drain of the first MOS transistor via a first diode, and the inverting input terminal is grounded. The first feedback resistor is disposed between the output terminal and the inverting input terminal of the first operational amplifier.

[0010] Furthermore, the signal filtering circuit includes a signal filtering resistor and a signal filtering capacitor. The first end of the signal filtering resistor is connected to the output terminal of the first operational amplifier, and the second end is connected to the input terminal of the signal output circuit. The signal filtering capacitor is disposed between the second end of the signal filtering resistor and ground.

[0011] Furthermore, the signal output circuit includes a first control chip, the input terminal of which is connected to the output terminal of the first operational amplifier via the signal filtering circuit, and the output terminal outputs a driving signal to the LED driving circuit.

[0012] Furthermore, the sustaining circuit includes a sustaining load circuit, a second MOSFET, a second voltage divider resistor group, and a second three-terminal regulator. The drain and source of the second MOSFET are connected in series in the sustaining load circuit. The input terminal of the second voltage divider resistor group is connected to the output terminal of the diode rectifier circuit, and the voltage divider output terminal is connected to the reference terminal of the second three-terminal regulator. The anode of the second three-terminal regulator is grounded, and the cathode is connected to the gate of the second MOSFET.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] The phase of the output power supply of the SCR dimmer changes, causing voltage variations. In the phase detection circuit, after voltage division, the three-terminal regulator controls the brightness of the LED in the optocoupler, thus generating PWM detection signals of different widths on the output side of the optocoupler. The PWM detection signals are isolated, converted, amplified, and filtered before being input to the control chip in the signal output circuit. The control chip then outputs corresponding PWM drive signals to the LED driver circuit according to the phase of the SCR dimmer, performing dimming control. This effectively ensures the stable operation of the LED, while eliminating the need to add a large number of RC filters and smoothing resistors on the input and output sides. When the SCR is working, the sustaining circuit also provides sustaining current for the SCR. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall principle structure of an embodiment of the present utility model;

[0016] Figure 2 This is a schematic diagram of the principle structure of the sustaining circuit and the phase detection circuit in an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the signal amplification circuit according to an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the signal output circuit in an embodiment of the present invention. Detailed Implementation

[0019] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] In the description of this specification, references to terms such as "embodiment," "one embodiment," and "one implementation" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0022] like Figure 1 As shown, this utility model provides a thyristor detection and sustaining circuit, including: a diode rectifier circuit, a sustaining circuit, a phase detection circuit, a signal amplification circuit, a signal filtering circuit, and a signal output circuit. The input terminal of the diode rectifier circuit is connected to an AC voltage input regulated by the thyristor. The sustaining circuit is connected to the output terminal of the diode rectifier circuit to provide a sustaining current for the thyristor. The phase detection circuit is connected to the output terminal of the diode rectifier circuit to output a corresponding detection signal based on the detected voltage phase. The input terminal of the signal amplification circuit is connected to the output terminal of the phase detection circuit, and its output terminal is connected to the input terminal of the signal filtering circuit. The output terminal of the signal filtering circuit is connected to the input terminal of the signal output circuit. The output terminal of the signal output circuit outputs a driving signal to an LED driving circuit.

[0023] It should be noted that due to the different phases of the output power supply of the SCR dimmer, the voltage changes. In the phase detection circuit, after voltage division, the three-terminal regulator controls the brightness change of the LED in the optocoupler, thereby forming PWM detection signals of different widths on the output side of the optocoupler. The PWM detection signals are converted, amplified, and filtered before being input to the control chip in the signal output circuit. The control chip then outputs the corresponding PWM drive signal to the LED driver circuit according to the phase of the SCR dimmer, performing dimming control, which effectively ensures the stable operation of the LED. At the same time, there is no need to add a large number of RC filters and smoothing resistors on the input and output sides. When the SCR is working, the sustaining circuit also provides a sustaining current for the SCR. The output phase of the SCR dimmer refers to the time point when the SCR is turned on, i.e., the firing angle.

[0024] like Figure 2 As shown, the power signal adjusted by the thyristor dimmer is then input through diodes D301 and D302. At this time, in the sustaining circuit, resistors R300-R303 form a second voltage divider circuit, which divides the voltage according to the input voltage and outputs a voltage to the reference terminal of the second three-terminal regulator U300. Then, the second three-terminal regulator U300 controls the switching of the second MOSFET Q300 through the gate voltage of the second MOSFET Q300, controlling the on / off state of the sustaining load circuit. For example, when the drain and source of the second MOSFET Q300 are conducting, the input voltage will form a current through the circuit containing resistors R308-310. When the LED current is small, it forms a sustaining current for the thyristor.

[0025] In the phase detection circuit, resistors R312-R315 form the first voltage divider circuit, which outputs a voltage to the reference terminal of the second three-terminal regulator U302. The second three-terminal regulator U302 then controls the brightness of the LED of optocoupler U301A. Optocoupler U302B receives the signal from U302A and obtains PWM signals of different widths based on the output phase of the thyristor dimmer.

[0026] like Figure 3 As shown, the optocoupler U302B outputs PWM signals with different widths based on the output phase of the thyristor dimmer to the gate of the first MOSFET Q301. The drain of the first MOSFET Q301 receives a PWM signal opposite to the input. The PWM signal is filtered by the RC filter of resistor R335 and capacitors C330 and C331 to obtain an analog signal, which is then applied to the non-inverting input of the first operational amplifier U304. After being amplified by 1 time by the amplifier circuit formed by the first operational amplifier U304 and resistors R337 and R338, the signal is output from the output of the first operational amplifier U304. After being filtered again by resistor R339 and capacitor C333, the signal is output.

[0027] like Figure 4 As shown, the detection signal ADC1 is input to pin 20 of the control chip U303. The control chip U303 outputs a corresponding PWM drive signal to the subsequent LED driver circuit based on the phase detection of the thyristor. The model of the control chip U303 can be CMS 32L051TS20. The LED driver circuit is used to drive the LED lamp. Its structure is diverse. It can use a MOSFET connected in series with the LED lamp load circuit and control the MOSFET through the PWM drive signal to drive the LED lighting. Alternatively, it can use an LLC circuit to control the LED lighting, and the PWM drive signal is output to the switching transistor in the LLC circuit to drive the LED lighting.

[0028] Although the disclosure is as stated above, the scope of protection of this disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this utility model.

Claims

1. A thyristor detection and sustaining circuit, characterized in that, include: The system includes a diode rectifier circuit, a sustaining circuit, a phase detection circuit, a signal amplification circuit, a signal filtering circuit, and a signal output circuit. The input terminal of the diode rectifier circuit is connected to an AC voltage input regulated by a thyristor. The sustaining circuit is connected to the output terminal of the diode rectifier circuit to provide sustaining current for the thyristor. The phase detection circuit is connected to the output terminal of the diode rectifier circuit to output a corresponding detection signal based on the detected voltage phase. The input terminal of the signal amplification circuit is connected to the output terminal of the phase detection circuit, and its output terminal is connected to the input terminal of the signal filtering circuit. The output terminal of the signal filtering circuit is connected to the input terminal of the signal output circuit. The output terminal of the signal output circuit outputs a driving signal to the LED driver circuit.

2. The thyristor detection and sustaining circuit according to claim 1, characterized in that, The phase detection circuit includes a first voltage divider resistor group, a first three-terminal regulator, and a first optocoupler. The input terminal of the first voltage divider resistor group is connected to the output terminal of the diode rectifier circuit, the voltage divider output terminal is connected to the reference terminal of the first three-terminal regulator, the anode of the first three-terminal regulator is grounded, and the cathode is connected to the power supply via the input side of the first optocoupler.

3. The thyristor detection and sustaining circuit according to claim 2, characterized in that, The signal amplification circuit includes an inverting isolation circuit and an operational amplifier circuit connected in sequence.

4. The thyristor detection and sustaining circuit according to claim 3, characterized in that, The reverse isolation circuit includes a first MOS transistor, the gate and source of which are respectively connected to the two ends of the output side of the first optocoupler, and the drain of the first MOS transistor is connected to a 5V power supply.

5. The thyristor detection and sustaining circuit according to claim 4, characterized in that, The operational amplifier circuit includes a first operational amplifier and a first feedback resistor. The non-inverting input terminal of the first operational amplifier is connected to the drain of the first MOS transistor via a first diode, and the inverting input terminal is grounded. The first feedback resistor is disposed between the output terminal and the inverting input terminal of the first operational amplifier.

6. The thyristor detection and sustaining circuit according to claim 5, characterized in that, The signal filtering circuit includes a signal filtering resistor and a signal filtering capacitor. The first end of the signal filtering resistor is connected to the output terminal of the first operational amplifier, and the second end is connected to the input terminal of the signal output circuit. The signal filtering capacitor is disposed between the second end of the signal filtering resistor and ground.

7. The thyristor detection and sustaining circuit according to claim 5, characterized in that, The signal output circuit includes a first control chip. The input terminal of the first control chip is connected to the output terminal of the first operational amplifier via the signal filtering circuit, and the output terminal outputs a driving signal to the LED driving circuit.

8. The thyristor detection and sustaining circuit according to claim 1, characterized in that, The sustaining circuit includes a sustaining load circuit, a second MOSFET, a second voltage divider resistor group, and a second three-terminal regulator. The drain and source of the second MOSFET are connected in series in the sustaining load circuit. The input terminal of the second voltage divider resistor group is connected to the output terminal of the diode rectifier circuit, and the voltage divider output terminal is connected to the reference terminal of the second three-terminal regulator. The anode of the second three-terminal regulator is grounded, and the cathode is connected to the gate of the second MOSFET.

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