WO2019170105A1

WO2019170105A1 - Dimming circuit and light emitting device thereof

Info

Publication number: WO2019170105A1
Application number: PCT/CN2019/077178
Authority: WO
Inventors: 张显伟
Original assignee: 欧普照明股份有限公司
Priority date: 2018-03-06
Filing date: 2019-03-06
Publication date: 2019-09-12
Also published as: CN207947926U

Abstract

Disclosed are a dimming circuit and a light emitting device thereof. The dimming circuit comprises: a dimmer, a rectifier circuit, and an absorption circuit, wherein the output end of the dimmer is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is connected to the input end of the absorption circuit; the absorption circuit comprises a first capacitor, a first resistor, and a control switch module; the control switch module is connected in parallel with the first resistor. Since the control switch module is connected in parallel with the first resistor, when the control switch module is turned on, as the first resistor is in a short circuit state, the main current in the dimming circuit may not flow through the first resistor, so that the power loss of the first resistor in the absorption circuit can be reduced.

Description

Dimming circuit and light emitting device thereof

Technical field

The present application relates to the field of circuit technologies, and in particular, to a dimming circuit and a light emitting device thereof.

Background technique

At present, the use of thyristors for dimming light emitting diodes (LEDs) is one of the common LED dimming techniques. However, in the thyristor dimming circuit, when the brightness of the light is changed by the thyristor dimmer, the input voltage and current change instantaneously when the brightness of the light is changed, and the oscillation is easily generated in the circuit, thereby causing the circuit. unable to work properly.

In order to solve this problem, the prior art often eliminates the above-mentioned oscillation by adding an absorbing circuit, that is, the oscillating circuit can be added to eliminate the oscillation and improve the stability of the circuit. Figure 1 shows the thyristor dimming circuit, including: thyristor dimmer D, rectifier circuit DB1, capacitor CX1 for differential mode filtering, capacitor C1 for high frequency filtering, and RC snubber circuit R1 And C2. As shown in Fig. 2, in order to change the current and voltage transients in the circuit before and after the oscillating cancellation circuits R1 and C2 are added, it is obvious that after adding the RC absorbing circuits R1 and C2, the current in the circuit can be alleviated. The oscillation of the circuit when the voltage changes rapidly.

In the above scenario, due to the presence of the resistor R in the RC circuit, the power loss of the entire circuit is inevitably increased.

Summary of the invention

The embodiment of the present application provides a dimming circuit and a light emitting device thereof, which are used to solve the problem that the power loss of the entire dimming circuit is increased due to the presence of a resistor in the absorbing circuit in the existing dimming circuit.

The embodiment of the present application provides a dimming circuit, including: a dimmer, a rectifying circuit, and an absorbing circuit, wherein:

An output end of the dimmer is connected to an input end of the rectifier circuit, and an output end of the rectifier circuit is connected to an input end of the absorption circuit;

The snubber circuit includes a first capacitor, a first resistor, and a control switch module, the control switch module being coupled in parallel with the first resistor.

Preferably, the control switch module includes a reverse diode, a metal oxide semiconductor field effect transistor, a second capacitor, and a second resistor, wherein

One end of the first resistor is connected to the anode of the reverse diode, the cathode of the reverse diode is connected to the drain of the MOSFET, and the other end of the first resistor is a source connection of a metal oxide semiconductor field effect transistor;

Two ends of the second capacitor are respectively connected to a gate of the MOSFET and a source of the MOSFET, and the second resistor is connected in parallel with the second capacitor.

Preferably, the control switch module includes a triode, a second capacitor, and a second resistor, wherein

One end of the first resistor is connected to a pole electrode of the triode, and the other end of the first resistor is connected to an emitter of the triode;

Two ends of the second capacitor are respectively connected to the base and the emitter of the transistor, and the second resistor is connected in parallel with the second capacitor.

Preferably, the metal oxide semiconductor field effect transistor is an N-type metal oxide semiconductor field effect transistor.

Preferably, when the second capacitor is charged to reach a gate-on voltage of the MOS transistor, the MOSFET is in an on state.

Preferably, the control switch module comprises an SCR thyristor rectifying element, a second capacitor and a second resistor, wherein

One end of the first resistor is connected to an anode of the SCR, and the other end of the first resistor is connected to a cathode of the SCR;

Two ends of the second capacitor are respectively connected to a control electrode of the SCR and a cathode of the SCR; and the second resistor is connected in parallel with the second capacitor.

Preferably, when the second capacitor is charged to reach the gate-opening voltage of the SCR, the SCR is in an on state.

Preferably, the dimming circuit further includes a third capacitor and a fourth capacitor, wherein

Two ends of the third capacitor are respectively connected to two input ends of the rectifier circuit;

Two DC output ends of the rectifier circuit are respectively connected to both ends of the fourth capacitor;

The fourth capacitor is connected in parallel with the absorption circuit.

Preferably, the control switch module comprises a digital switch.

The embodiment of the present application further provides a light emitting device, including the dimming circuit and the light fixture described above.

The above at least one technical solution adopted by the embodiment of the present application can achieve the following beneficial effects:

The dimming circuit provided by the embodiment of the present application includes a dimmer, a rectifying circuit and an absorbing circuit, wherein the absorbing circuit comprises a first capacitor, a first resistor and a control switch module, and the parallel connection of the control switch module and the first resistor When the control switch module is in the on state, since the first resistor is in the short circuit state, the main current in the dimming circuit will not flow through the first resistor, and the power loss of the first resistor in the absorbing circuit can be reduced.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the present application, and are intended to be a part of this application. In the drawing:

1 is a schematic structural view of a dimming circuit in the prior art;

2 is a comparison diagram of changes in current and voltage when the dimming circuit of the prior art is dimmed before and after the absorbing circuit is added;

FIG. 3 is a schematic structural diagram of a dimming circuit according to an embodiment of the present disclosure;

4 is a schematic structural diagram of a specific implementation manner of a dimming circuit according to an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of another implementation manner of a dimming circuit according to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a specific implementation manner of another dimming circuit according to an embodiment of the present application.

Detailed ways

In order to solve the above problems in the prior art, the embodiment of the present application provides a dimming circuit and a device thereof. Compared with the prior art, the dimming circuit adds a control switch module to the RC absorbing circuit. The resistors in the control switch module RC absorbing circuit are connected in parallel. When the control switch module is in the on state, the resistance in the RC snubber circuit is in a short circuit state, so that the RC snubber circuit can be reduced when the control switch module is in the on state. The power loss of the medium resistor.

The technical solutions of the present application are clearly and completely described below in conjunction with the specific embodiments of the present application and the corresponding drawings. It is apparent that the described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the inventive scope are the scope of the present application.

Please refer to FIG. 3 , which is a schematic structural diagram of a dimming circuit provided by the embodiment. The dimming circuit includes: a dimmer D, a rectifying circuit DB1, and an absorbing circuit X. The output end of the dimmer D is connected to the input end of the rectifying circuit DB1, and the output end of the rectifying circuit DB1 and the absorbing circuit X The input terminal is connected, and the absorbing circuit X includes a first capacitor C2, a first resistor R1 and a control switch module Q. The control switch module Q is connected in parallel with the first resistor R1. Wherein, the dimmer D can be a thyristor dimmer. When the current voltage in the dimming circuit is in a steady state, the power loss of the first resistor R1 in the absorbing circuit X can be reduced by controlling the conduction of the switching module Q.

The rectifier circuit may be a rectifier bridge, that is, bridge rectifier, and the rectifier bridge may be full-wave rectification and half-wave rectification in practical applications.

In practical applications, the control switch module Q can have the following three implementation modes:

First, referring to FIG. 4, the control switch module Q includes a reverse diode D1, a metal oxide semiconductor field effect transistor (MOS) Q1, a second capacitor C3, and a second resistor R2, wherein the first One end of the resistor R1 is connected to the anode of the reverse diode D1, the cathode of the reverse diode D1 is connected to the drain of the MOS transistor Q1, and the other end of the first resistor R1 is connected to the source of the MOS transistor; both ends of the second capacitor C3 Connected to the gate of the MOS transistor Q1 and the source of the MOS transistor Q1, respectively; the second resistor R2 is connected in parallel with the second capacitor C3. Wherein, the metal oxide semiconductor field effect transistor is an N-type metal oxide semiconductor field effect transistor.

When the first capacitor C2 is charged, the MOS transistor Q1 is delayed in conduction due to the charging delay of the C3 capacitor, and the current flows through the first resistor R1 when the C2 is charged. Therefore, R1 can absorb the oscillation at this time.

When the second capacitor C3 is charged to reach the gate turn-on voltage of the MOS transistor Q1, the MOS transistor Q1 is in an on state, and when the MOS transistor Q1 is in an on state, the first resistor R1 is in a short-circuit state. At this time, the circuit The main current in the current only flows through the reverse diode D1 and the MOS transistor Q1, and since the on-resistance of the MOS transistor Q1 is small, the power loss of the reverse diode D1 is also relatively small, so at this time in the MOS transistor Q1 and the opposite The power loss to the diode D1 is negligible, so that the power loss of the dimming circuit can be reduced.

When the first capacitor C2 is in the discharging state, the discharge current can be prevented from forming a loop in the MOS tube due to the presence of the reverse diode D1 in the circuit.

Secondly, please participate in FIG. 5, the control switch module comprises a transistor Q2, a second capacitor C3 and a second resistor R2, wherein one end of the first resistor R1 is connected to the source of the transistor Q2, and the other end of the first resistor R1 Connected to the drain of the transistor Q2; the two ends of the second capacitor C3 are respectively connected to the gate and the drain of the transistor Q2; the second resistor R2 is connected in parallel with the second capacitor C3.

When the second capacitor C3 is charged to reach the gate turn-on voltage of the transistor Q2, the transistor Q2 is in an on state, and when the transistor Q2 is in an on state, the first resistor R1 is in a short circuit state. At this time, the main circuit is The current flows only through the transistor Q2, and since the on-resistance of the transistor Q2 is small, the power loss on the transistor Q2 is negligible at this time, so that the power loss of the dimming circuit can be reduced.

Third, please participate in FIG. 6, the control switch module includes an SCR thyristor rectifying element Q3, a second capacitor C3, and a second resistor R2, wherein one end of the first resistor R1 is connected to the anode of the SCR, first The other end of the resistor R1 is connected to the cathode of the SCR; the two ends of the second capacitor C3 are respectively connected to the control pole of the SCR and the cathode of the SCR; and the second resistor R2 is connected in parallel with the second capacitor C3.

When the second capacitor C3 is charged to reach the gate-opening voltage of the SDR, the SDR is in an on state, and when the SDR is in an on state, the first resistor R1 is in a short-circuit state, and at this time, the main current in the circuit flows only. With SDR, since the on-resistance of the SDR is small, the power loss on the SDR is negligible at this time, so that the power loss of the dimming circuit can be reduced.

Optionally, the above control switch module can also be implemented by a digital switch in practical applications.

In addition, in order to filter differential mode interference and high frequency interference in the circuit, the dimming circuit may further include a third capacitor CX1 and a fourth capacitor C1, wherein two ends of the third capacitor CX1 and the rectifier circuit DB1 are respectively The input terminals are connected, the third capacitor CX1 is used for filtering the differential mode interference in the circuit; the two DC output ends of the rectifier circuit DB1 are respectively connected with the two ends of the fourth capacitor C1, and the fourth capacitor C1 and the absorption circuit X In parallel, the fourth capacitor C1 is used to filter out high frequency interference in the circuit.

The embodiment of the present application further provides a light fixture, which may include a light emitting device and the above dimming circuit. The illuminating device comprises a substrate and an LED disposed on the substrate, the luminaire further comprising a lamp body set, the illuminating device and the driving component are provided with the dimming circuit and electrically connected to the illuminating device.

It will be apparent to those skilled in the art that <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and the modifications and

It will be apparent to those skilled in the art that various modifications and changes can be made in the present application without departing from the scope of the application. Thus, it is intended that the present invention cover the modifications and variations of the present invention.

Claims

A dimming circuit, comprising: a dimmer, a rectifying circuit and an absorbing circuit, wherein:

An output end of the dimmer is connected to an input end of the rectifier circuit, and an output end of the rectifier circuit is connected to an input end of the absorption circuit;

The snubber circuit includes a first capacitor, a first resistor, and a control switch module, the control switch module being coupled in parallel with the first resistor.
The dimming circuit according to claim 1, wherein the control switch module comprises a reverse diode, a metal oxide semiconductor field effect transistor, a second capacitor and a second resistor, wherein

One end of the first resistor is connected to the anode of the reverse diode, the cathode of the reverse diode is connected to the drain of the MOSFET, and the other end of the first resistor is a source connection of a metal oxide semiconductor field effect transistor;

Two ends of the second capacitor are respectively connected to a gate of the MOSFET and a source of the MOSFET, and the second resistor is connected in parallel with the second capacitor.
The dimming circuit according to claim 2, wherein said metal oxide semiconductor field effect transistor is an N-type metal oxide semiconductor field effect transistor.
The dimming circuit according to claim 2, wherein said MOSFET is in an on state when said second capacitor is charged to reach a gate-on voltage of said MOS transistor.
The dimming circuit according to claim 1, wherein the control switch module comprises a triode, a second capacitor and a second resistor, wherein

One end of the first resistor is connected to a pole electrode of the triode, and the other end of the first resistor is connected to an emitter of the triode;

Two ends of the second capacitor are respectively connected to the base and the emitter of the transistor, and the second resistor is connected in parallel with the second capacitor.
The dimming circuit according to claim 1, wherein the control switch module comprises an SCR thyristor rectifying element, a second capacitor and a second resistor, wherein

One end of the first resistor is connected to an anode of the SCR, and the other end of the first resistor is connected to a cathode of the SCR;

Two ends of the second capacitor are respectively connected to a control electrode of the SCR and a cathode of the SCR; and the second resistor is connected in parallel with the second capacitor.
The dimming circuit according to claim 6, wherein said SCR is in an on state when said second capacitor is charged to reach a gate-opening voltage of said SCR.
The dimming circuit according to claim 1, wherein the dimming circuit further comprises a third capacitor and a fourth capacitor, wherein

Two ends of the third capacitor are respectively connected to two input ends of the rectifier circuit;

Two DC output ends of the rectifier circuit are respectively connected to both ends of the fourth capacitor;

The fourth capacitor is connected in parallel with the absorption circuit.
The dimming circuit of claim 1 wherein said control switch module comprises a digital switch.
A light emitting device, comprising: the dimming circuit and the luminaire according to any one of claims 1 to 7.