CN110602829B

CN110602829B - Lighting LED driving circuit, device and control method

Info

Publication number: CN110602829B
Application number: CN201910915964.1A
Authority: CN
Inventors: 王继业
Original assignee: Minzu University of China
Current assignee: Minzu University of China
Priority date: 2019-09-26
Filing date: 2019-09-26
Publication date: 2021-11-16
Anticipated expiration: 2039-09-26
Also published as: CN110602829A

Abstract

An illumination LED driver circuit comprising: the LED lamp comprises a rectification filter circuit, a control circuit, a switching circuit and a light-emitting circuit, wherein the rectification filter circuit is used for converting input alternating-current voltage into high-voltage direct-current voltage; the control circuit is used for controlling the switch circuit, the switch circuit at least has a first working state to a third working state, and the control circuit controls the switch circuit to periodically work in the first working state to the third working state; the switch circuit is used for being controlled by the control circuit to periodically switch among the first working state component, the second working state component and the third working state component so as to realize the control of the light-emitting circuit. The circuit is simplified, and the cost is reduced.

Description

Lighting LED driving circuit, device and control method

Technical Field

The invention relates to the technical field of lighting circuits, in particular to a lighting LED driving circuit, a device and a control method.

Background

The LED has high lighting efficiency and long service life, and is the first choice of lighting engineering. LED dimming can be achieved by both current regulation and duty cycle regulation. When the current is changed, the light emitting characteristics of the light emitting diode are different, and thus, when the light is dimmed, the color of light or the like is changed. Therefore, dimming current is not a good way to dim.

It is currently preferred to overcome these disadvantages by varying the duty cycle of the supply current to dim. The general circuit is a common AD-DC power supply to obtain a stable direct current voltage, and then Pulse Width Modulation (PWM) voltages with different duty ratios are obtained after chopping by a switching element, so that the proportion of the LED conducting time in the whole period is changed, and the dimming effect is formed.

The circuit is complex, high in cost and large in size.

Disclosure of Invention

The invention aims to provide an illumination LED drive circuit, which comprises: a rectifying and filtering circuit, a control circuit, a switch circuit and a light-emitting circuit, wherein,

the rectification filter circuit is used for converting the input alternating voltage into high-voltage direct current voltage;

the control circuit is used for controlling the switch circuit, the switch circuit at least has a first working state to a third working state, and the control circuit controls the switch circuit to periodically work in the first working state to the third working state;

the switch circuit is used for being controlled by the control circuit to periodically switch among the first working state component, the second working state component and the third working state component so as to realize the control of the light-emitting circuit.

In some embodiments, the switching circuit comprises a transformer configured with one primary coil and at least two secondary coils, a first switching device, a second switching device, a first diode;

the first switching device, the primary coil and the output end of the rectifying and filtering circuit are connected in series to form a first loop;

the second switching device, a first secondary coil of the at least two secondary coils and a first diode are sequentially connected in series to form a second loop;

the control circuit controls the first switching device and the second switching device to realize the on-off of the first loop and the second loop.

In some embodiments, the switching circuit further comprises a current detection circuit connected in series between the negative output terminal of the rectifying-filtering circuit and the first switching device.

In some embodiments, the light emitting circuit includes a light emitting module group corresponding to each of the at least two secondary coils except for a first secondary coil, and the light emitting module group is connected in series with the corresponding secondary coil through a second diode.

In some embodiments, the present invention also provides an illumination LED device comprising the illumination LED driving circuit described in any of the preceding embodiments.

In some embodiments, the present invention further provides a method for controlling an illumination LED driving circuit, which is applied to the illumination LED driving circuit described in the foregoing embodiments, the method including:

the control circuit controls the switching circuit to periodically work in the first working state, the second working state and the third working state; wherein the content of the first and second substances,

the first working state is as follows: the first switch device is turned on, the second switch device is turned off, the first coil stores energy, the second diode and the third diode are turned off, and the light-emitting circuit does not emit light;

the second working state is as follows: the first switch device is turned off, the second diode and the third diode are turned on, and the light-emitting circuit emits light;

the third working state is as follows: the first switching device is turned off, the second switching device is turned on, the second diode and the third diode are turned off, and the light emitting circuit does not emit light.

The flyback switching power supply and the LED modulation circuit are combined simply, so that the LED dimming circuit is greatly simplified, the cost is reduced, the control is simplified, and the size is reduced.

Drawings

FIG. 1 is a schematic diagram of one embodiment of an illumination LED driver circuit according to the present invention;

fig. 2 is a schematic circuit diagram of another embodiment of the LED driving circuit of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings.

The inventor finds that in the process of implementing the invention, one switching power supply consists of a primary switching device, a pulse transformer and a secondary rectifying and filtering circuit, and the secondary direct-current voltage is chopped by the switching device to form repetition. If the switching device of the switching power supply is skillfully utilized to carry out switching conversion and simultaneously realize secondary chopping and PWM modulation, the aim of dimming is achieved, the LED power supply circuit is greatly simplified, the cost is saved, and the size is reduced.

As shown in fig. 1, a schematic circuit diagram of an embodiment of an illumination LED driving circuit according to the present invention includes: a rectifying and filtering circuit 10, a control circuit 20, a switching circuit 30 and a light emitting circuit 40. Wherein the content of the first and second substances,

a rectifier filter circuit 10 for converting an input ac voltage into a high-voltage dc voltage;

the control circuit 20 is used for controlling the switch circuit 30, the switch circuit 30 at least has a first working state to a third working state, and the control circuit 20 controls the switch circuit 30 to periodically work in the first working state to the third working state;

the switch circuit 30 is used for being controlled by the control circuit 20 to periodically switch between the first operating state and the third operating state to realize the control of the light-emitting circuit 40.

As shown in fig. 2, according to another embodiment of the present application, the switching circuit includes a transformer, a first switching device, a second switching device, and a first diode, wherein the transformer is configured with a primary winding and at least two secondary windings;

After the input commercial power passes through the rectifying and filtering circuit, the input commercial power becomes high-voltage direct current Vi. The rectifying and filtering circuit is not limited to the type, and may be a passive circuit or an active circuit. The high-voltage direct current Vi is connected in series with a coil N1 of a transformer T, a switching device Q1 and a current detection circuit.

The transformer T is composed of coils N1, N2, N3, N4, and the like.

The coil N2, the diode D1 and the switching device Q2 are connected in series to form a loop.

The coil N3 and the diode D2 and the LED light module LED3 form a loop. The LED3 is a dc powered LED module with current flow direction aligned with diode D2.

The coil N4, the diode D3 and the LED light module LED4 form a loop. Moreover, multiple sets of such circuits may be eliminated or added as needed.

The operation of the circuit can be divided into three stages of T1, T2 and T3.

At stage T1, Q1 is turned on, Q2 is turned off, and the loop is not turned on by the polarity relationship of the transformer T, the voltage induced in the coils (N2, N3, N4) and the diodes (D1, D2, D3) in the loop are in the opposite directions. N1 acts like an inductor, increasing the current and increasing the magnetic flux in the core of transformer T, storing energy.

During the T2 phase, Q1 is turned off and the T2 phase is entered. Since the Q1 and the Q2 are turned off, and the magnetic flux in the magnetic core cannot change abruptly, only the N3 and the N4 can generate current, the LED3 and the LED4 are powered through the diodes D2 and D3, and the LED emits light. The energy stored in the stage T1 is consumed by the LED lighting module, and the coil N2 loop induces voltage, but no current is generated due to Q2 cutoff.

And in the T3 stage, when the Q1 is turned off and the Q2 is turned on, the T3 stage is entered. At this time, the voltage induced in the coil N2 is very low due to the conduction of the Q2 in the loop of the coil N2, and the voltages induced in the coils N3 and N4 are also very low, so that the LEDs 3 and LED4 cannot emit light when conducting, therefore, only the loop of the coil N2 holds current, the energy loss is very small, and the energy loss can be considered to be approximately zero, and the magnetic flux is kept unchanged.

When the LED lamp works continuously, three stages form a period, only the T2 stage LED emits light, and the duty ratio D is T2/(T1+ T2+ T3). The light emission luminance can be changed by changing D.

The control circuit is used for generating signals to control the conduction and the cut-off of the Q1 and the Q2, and generating proper control timing. The control circuit controls the Q1 to be conducted and the Q2 to be cut off, and then the T1 stage is carried out. The control circuit turns Q1 off and Q2 off, and enters stage T2. The control circuit turns off Q1, turns on Q2, and enters stage T3.

The current detection circuit is connected in series in a loop of the coil N1 and is used for detecting the current in the T1 stage, and a detection output signal is connected to the control circuit. If closed-loop control is needed, the control circuit can adjust the ratio of the T1 and the T3 stages through the current signal to adjust the increase and decrease of the total magnetic flux and maintain the output current to be constant when the LED is conducted. The current sense signal may also be used for over-current protection of the circuit when Q1 is on. If closed-loop control and overcurrent protection are not required, the current detection circuit can be eliminated, so that the whole circuit is further simplified.

When the magnetic flux sensor works stably, the average magnetic flux of the whole period is not changed, and the following can be obtained:

N1×I1＝N2×I2＝N3×I3+N4×I4

the formula becomes the basis for designing the working current and the turn ratio.

In the period of T1, Q1 is turned on, Q2 is cut off, Vi is applied to the coil N1, voltages induced in the coils N2, N3 and N4 are respectively applied to the diodes D1, D2 and D3 in reverse directions, and the voltages are proportional to the number of turns, namely:

Vi/N1＝V2/N2＝V3/N3＝V4/N4

the formula becomes the basis for determining the withstand voltage and the number of turns of the diode.

The circuit is suitable for various switching devices, such as MOS (metal oxide semiconductor) transistors, VMOS (vertical metal oxide semiconductor) transistors, IGBT (insulated gate bipolar transistor), bipolar transistors and the like.

What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept herein, and it is intended to cover all such modifications and variations as fall within the scope of the invention.

Claims

1. An illumination LED driver circuit comprising: a rectifying and filtering circuit, a control circuit, a switch circuit and a light-emitting circuit, wherein,

the switch circuit is used for being controlled by the control circuit to periodically switch among the first working state component, the second working state component and the third working state component so as to realize the control of the light-emitting circuit;

the switching circuit comprises a transformer, a first switching device, a second switching device and a first diode, wherein the transformer is provided with a primary coil and at least two secondary coils;

the light-emitting circuit comprises light-emitting modules which are in one-to-one correspondence with each secondary coil except for a first secondary coil in the at least two secondary coils, and the light-emitting modules are connected with the corresponding secondary coils in series through second diodes;

the switching circuit includes;

2. The illumination LED drive circuit as set forth in claim 1, the switching circuit further comprising a current sense circuit connected in series between the negative output of the rectifying-filtering circuit and the first switching device.

3. The lighting LED driver circuit of claim 1, said light emitting module comprising a plurality of light emitting diodes and a current limiting resistor.

4. An illumination LED device comprising the illumination LED driving circuit according to any one of claims 1 to 3.

5. A lighting LED driving circuit control method applied to the lighting LED driving circuit of claim 3, the method comprising:

the first working state is as follows: the first switching device is switched on, the second switching device is switched off, the primary coil stores energy, the second diode is switched off, and the light-emitting circuit does not emit light;

the second working state is as follows: the first switch device is turned off, the second diode is turned on, and the light-emitting circuit emits light;

the third working state is as follows: the first switch device is turned off, the second switch device is turned on, the second diode is turned off, and the light emitting circuit does not emit light.