CN203467002U - LED constant-current power supply - Google Patents

Abstract

The utility model relates to the technical field of power supplies and particularly relates to an LED constant-current power supply. The LED constant-current power supply comprises a silicon controlled rectifier dimmer of which the input end is connected with an alternating-current power supply voltage and the output end is connected with a rectifier and filter circuit. A signal output end of the rectifier and filter circuit is connected with a current stabilization circuit. The current stabilization circuit has a control signal input end which is connected with a control circuit used for generating a control signal according to a reference voltage. The current stabilization circuit outputs a direct-current power supply voltage for supplying an adjustable drive power supply to an LED. According to the LED constant-current power supply, current output is stably controlled by a phase angle output by the silicon controlled rectifier dimmer so that an LED dimming effect can be achieved and both linear dimming and flexible dimming on the LED can be realized.

Description

A LED constant current power supply

technical field

The utility model relates to the technical field of power supplies, in particular to an LED power supply.

Background technique

The existing dimming technology for ordinary light sources (incandescent lamps) is mainly thyristor phase modulation dimming, which has a large number of applications in the actual dimming field. LED lighting has been used more and more widely due to a series of advantages. However, the existing LED lighting power supply based on the traditional thyristor dimmer design has dark light instability, and there are flickering points and dimming points during the dimming process. Uneven light and other issues.

Utility model content

The purpose of the utility model is to provide an LED constant current power supply to solve the above technical problems. The technical problem solved by the utility model can be realized by adopting the following technical solutions:

A LED constant current power supply, which includes a thyristor dimmer, the input end of the thyristor dimmer is connected to an AC power supply voltage, and the output end of the thyristor dimmer is connected to a rectification filter circuit The signal output end of the rectification filter circuit is connected to a steady current circuit; the steady current circuit is provided with a control signal input end, and the control signal input end is connected to a control circuit for generating a control signal;

The current stabilizing circuit outputs a DC power supply voltage for providing adjustable driving power for the LED.

Preferably, the rectifying and filtering circuit includes a rectifying circuit and a filtering circuit, the output of the rectifying circuit is connected to the filtering circuit; the rectifying circuit is used to convert alternating current into direct current; the filtering circuit is used to filter Ripple in the output voltage of a rectifier circuit.

Preferably, the rectifier circuit is also connected to a voltage stabilizing circuit, the voltage stabilizing circuit is provided with a signal output terminal for providing phase information to the control circuit, and the signal output terminal is connected to the control circuit.

Preferably, a DC-DC voltage conversion module is provided between the rectification and filtering circuit and the current stabilization circuit.

Preferably, the DC-DC voltage conversion module adopts a boost circuit.

Preferably, the filter circuit includes a diode and an electrolytic capacitor connected in series with the diode, the anode of the diode is connected to the output end of the rectifier circuit, and the cathode of the diode is connected to the anode of the electrolytic capacitor, so The cathode of the electrolytic capacitor is grounded.

Preferably, the rectification circuit adopts a bridge rectification circuit.

Preferably, the voltage stabilizing circuit includes a current limiting resistor and a voltage stabilizing tube connected in series with the current limiting resistor, and the signal output terminal is drawn out between the current limiting resistor and the voltage stabilizing tube.

Preferably, the control circuit includes a microprocessor, the microprocessor is provided with at least two input and output ports, and the signal output terminal of the voltage stabilizing circuit is connected to one of the input and output ports; the microprocessor passes The other input and output port is connected to a signal processing unit;

The microprocessor is also connected to a storage unit, the storage unit stores the dimming phase angle and the corresponding linear control current value, and the microprocessor measures the dimming phase angle through the signal input from the signal output terminal, And the linear control current value is obtained through the query of the storage unit; the microprocessor outputs an adjustment signal corresponding to the duty ratio to the signal processing unit, and the control signal input of the steady current circuit is connected through the signal processing unit The terminal is used to control the size of the LED drive current.

Preferably, the signal processing unit includes an RC filter unit and an operational amplification unit connected to the RC filter unit.

Preferably, the control circuit adopts a control circuit composed of an RC filter unit and an operational amplification unit connected to the RC filter unit, and the signal output terminal of the voltage stabilizing circuit is connected to the signal input terminal of the RC filter unit .

Beneficial effects: due to the adoption of the above technical scheme, the utility model can stably control its current output by the phase angle output by the thyristor dimmer, so as to achieve the dimming effect on the LED, and can realize the linear dimming and flexible dimming of the LED .

Description of drawings

Fig. 1 is the circuit connection schematic diagram of the present utility model;

Fig. 2 is the output voltage waveform diagram of the AC power supply voltage of the utility model after the thyristor dimmer;

Fig. 3 is the output voltage waveform diagram of the AC power supply voltage of the present utility model after the bridge rectifier circuit;

Fig. 4 is the voltage waveform diagram of the input signal of the control circuit of the present utility model;

Fig. 5 is a kind of circuit structure diagram of the control circuit of the present utility model;

FIG. 6 is a schematic diagram of another circuit structure of the control circuit of the present invention.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the utility model.

Referring to Figure 1, a LED constant current power supply includes a thyristor dimmer 1, the input end of the thyristor dimmer 1 is connected to the AC power supply voltage (VAC), and the output end of the thyristor dimmer 1 is connected to A rectification and filtering circuit; the signal output end of the rectification and filtering circuit is connected to a steady current circuit 5; the steady current circuit 5 is provided with a control signal input end, and the control signal input end is connected to a control circuit 6 for generating a control signal; the steady current circuit 5 The output DC supply voltage is used to provide adjustable driving power for LEDs.

The rectification filter circuit includes a rectification circuit 2 and a filter circuit 3, the output end of the rectification circuit 2 is connected to the filter circuit 3; the rectification circuit 2 is also connected to a voltage stabilizing circuit 7, and the voltage stabilizing circuit 7 includes a current limiting resistor (R1) and A voltage regulator tube (Z1) connected in series with a current limiting resistor, a signal output terminal for providing phase information to the control circuit is drawn between the current limiting resistor and the voltage regulator tube, and the signal output terminal is connected to the control circuit 6 . The rectification circuit 2 is used to convert the alternating current into direct current; the rectification circuit 2 may adopt a bridge rectification circuit 2 . The filter circuit 3 is used to filter the ripple in the output voltage of the rectifier circuit 2. The filter circuit 3 may include a diode (D1) and an electrolytic capacitor (E1) connected in series with the diode. The anode of the diode is connected to the output terminal of the rectifier circuit 2. The cathode of the diode is connected to the anode of the electrolytic capacitor, and the cathode of the electrolytic capacitor is grounded. Further, a DC-DC voltage conversion module is provided between the rectification filter circuit 3 and the current stabilization circuit 5 . The DC-DC voltage conversion module adopts a boost circuit 4 .

图4的矩形波经控制电路6后输出一个控制模拟量，用以控制稳流电路5的输出电流大小，从而实现LED光源的调光。When working, the AC power supply voltage (VAC) outputs a voltage waveform as shown in Figure 2 after passing through the thyristor dimmer 1, and after passing through the bridge rectifier circuit, the waveform shown in Figure 3 is obtained at point A (set G point is the reference zero potential). The electrolytic capacitor of the filter circuit 3 is a large-capacity electrolytic capacitor. Due to the isolation of the diode, the voltage at point C is approximately a stable DC, and the value is about the peak value (Vc) of the waveform in Figure 3. After the voltage at point A is limited by the current limiting resistor and the Zener tube, the waveform shown in Figure 4 is obtained at point F, where the peak value (Vz1) of the waveform shown in Figure 4 is one to the AC power supply voltage (VAC). A small amount, so the figure is a rectangular wave, whose duty cycle directly reflects the conduction phase angle of the output of the thyristor dimmer 1

The rectangular wave in Fig. 4 outputs a control analog quantity after passing through the control circuit 6, which is used to control the output current of the current stabilizing circuit 5, so as to realize the dimming of the LED light source.

The boost circuit 4 in FIG. 1 is implemented by a switch boost circuit, and the voltage at point D can be stabilized at the maximum peak value of the input voltage (VAC). The steady current circuit 5 in Fig. 1 is implemented by a switch type steady current circuit, and its output current is controlled by the voltage at point E.

The control circuit 6 can be realized by the above circuit: with reference to Fig. 5, the control circuit 6 includes a microprocessor 61, the microprocessor 61 is provided with at least two input and output ports, and the signal output end of the voltage stabilizing circuit 7 is connected to an input and output port; The microprocessor 61 is connected to a signal processing unit through another input and output port; the signal processing unit may include an RC filter unit 62 and an operational amplification unit 63 connected to the RC filter unit 62 . The microprocessor 61 includes a storage unit, which stores the dimming phase angle and the corresponding linear control current value. The microprocessor 61 measures the dimming phase angle through the signal input from the signal output terminal, and queries the dimming phase angle through the storage unit. The linear control current value is obtained; the microprocessor 61 outputs an adjustment signal corresponding to the duty ratio to the signal processing unit, and the signal processing unit is connected to the control signal input terminal of the current stabilization circuit to control the LED driving current. This control method can not only achieve linear control of light output, but also realize flexible dimming through control software algorithms, that is, the response rate of dimming can be controlled at will to avoid sudden changes and fluctuations in light caused by external factors.

It is also possible to short-circuit the microprocessor 61 in FIG. 5, the signal at point F is directly sent to the RC filter unit 62 without passing through the microprocessor 61, and then the output signal is given to the current stabilization circuit 5 to control the size of the LED driving current. This is a simple control method that can realize stable dimming of the LED from dark to dark, but the dimming position of the dimmer is not in a linear relationship with the light output of the LED, so the circuit structure shown in Figure 5 is preferred.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the implementation and protection scope of the present utility model. For those skilled in the art, they should be aware The schemes obtained by making equivalent replacements and obvious changes shall all be included in the protection scope of the present utility model.

Claims (10)

1. A kind of LED constant current power supply, it is characterized in that, comprises a silicon controlled rectifier dimmer, the input end of described silicon controlled rectifier dimmer is connected to AC power supply voltage, the output end of described silicon controlled rectifier dimmer is connected A rectification and filtering circuit; the signal output end of the rectification and filtering circuit is connected to a steady current circuit; the steady current circuit is provided with a control signal input end, and the control signal input end is connected to a control circuit for generating a control signal; The current stabilizing circuit outputs a DC power supply voltage for providing adjustable driving power for the LED. the 2 . The LED constant current power supply according to claim 1 , wherein the rectifying and filtering circuit comprises a rectifying circuit and a filtering circuit, and an output end of the rectifying circuit is connected to the filtering circuit. 3 . the 3. A LED constant current power supply according to claim 2, wherein the rectifier circuit is also connected to a voltage stabilizing circuit, and the voltage stabilizing circuit is provided with a signal output terminal for providing phase information to the control circuit , the signal output terminal is connected to the control circuit. the 4 . The LED constant current power supply according to claim 3 , wherein a DC-DC voltage conversion module is provided between the rectification filter circuit and the current stabilization circuit. the 5. A LED constant current power supply according to claim 2, wherein the filter circuit comprises a diode and an electrolytic capacitor connected in series with the diode, the anode of the diode is connected to the output terminal of the rectifier circuit connected, the cathode of the diode is connected to the anode of the electrolytic capacitor, and the cathode of the electrolytic capacitor is grounded. the 6 . The LED constant current power supply according to claim 2 , wherein the rectification circuit adopts a bridge rectification circuit. the 7. A LED constant current power supply according to claim 3, characterized in that the voltage stabilizing circuit comprises a current limiting resistor and a voltage stabilizing tube connected in series with the current limiting resistor, and the current limiting resistor and the The signal output terminal is drawn between the voltage regulator tubes. the 8. A LED constant current power supply according to claim 3, wherein the control circuit comprises a microprocessor, the microprocessor is provided with at least two input and output ports, and the voltage stabilizing circuit The signal output terminal is connected to one of the input and output ports; the microprocessor is connected to a signal processing unit through another input and output port; The microprocessor includes a storage unit, which stores the dimming phase angle and the corresponding linear control current value. the 9 . The LED constant current power supply according to claim 8 , wherein the signal processing unit comprises an RC filter unit and an operational amplification unit connected to the RC filter unit. the 10. A LED constant current power supply according to claim 3, characterized in that, the control circuit adopts a control circuit composed of an RC filter unit and an operational amplification unit connected to the RC filter unit, the The signal output end of the voltage stabilizing circuit is connected to the signal input end of the RC filter unit. the

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