CN201256471Y - Light emitting diode driving circuit - Google Patents

Abstract

The utility model relates to a light emitting diode driving circuit, which is connected with an electric power source to generate an output electric power to drive at least one light emitting diode, it comprises a power factor correction circuit, a power conversion unit, a pulse width modulation unit and an impedance modulation unit, the pulse width modulation unit generates a pulse signal for turning on a switch unit to determine the on/off of the switch unit, and the switch unit determines the timing of the input power flowing through the power factor correction circuit and the power conversion unit, wherein at least two power paths with different impedances are arranged between the impedance modulation unit and the switch unit, and extracting a voltage detection signal from the input power for the impedance modulation unit to switch to a power path with different equivalent impedance values to adjust the magnitude of the feedback signal, thereby improving the defect of power factor reduction caused by the rise of the input power.

Description

LED driver circuit

technical field

The utility model relates to a drive circuit, in particular to a light-emitting diode drive circuit which controls the pulse width of the input power according to the input power of a power source to adjust its power factor.

Background technique

In recent years, due to the demand for energy control and environmental protection, in order to avoid energy waste, improving the power factor has become an important consideration in the design of today's electronic equipment, and the power factor refers to the effective power and total power consumption (apparent power). The relationship between the effective power and the total power consumption (apparent power), the closer the effective power is to the total power consumption, the higher the power factor, that is, the better the work efficiency, and the improvement of work efficiency will reach the actual The advantages of increased output power, reduced loss and reduced waste heat, coupled with the safety regulations and harmonic regulations announced by the European Union, have high standards for the power efficiency of various electronic products, so that all industries must devote themselves to improving product power consumption. With the widespread use of light-emitting diodes (ie, diodes, referred to herein as diodes), how to improve the power factor of the light-emitting diode driving circuit has become a problem that manufacturers must face.

In the current existing technology, the structure of the driving circuit of the light-emitting diode is shown in Figure 1. The input power is transmitted to a power conversion unit 20 through a power factor correction circuit 60 to be converted into output power to drive the light-emitting diode 30 to emit light, and the circuit The structure further includes a pulse width modulation unit 40, the pulse width modulation unit 40 obtains a feedback signal S1 from the power conversion unit 20 through the feedback control unit 90, and adjusts the pulse wave of the input power according to the magnitude of the feedback signal S1 Width, when the input power is increased, the pulse width of the input power is reduced by the pulse width modulation unit 40 to maintain the stability of the output power. The absence of losses and increased production costs.

It can be seen that the above-mentioned existing light emitting diode driving circuit obviously still has inconvenience and defects in structure and use, and needs to be further improved urgently. In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and the general products do not have a suitable structure to solve the above-mentioned problems. This is obviously the relevant industry. urgent problem to be solved. Therefore, how to create a new type of light-emitting diode driving circuit is one of the current important research and development topics, and it has also become a goal that the industry needs to improve.

In view of the above-mentioned defects existing in the existing light-emitting diode driving circuit, the inventor actively researches and innovates on the basis of years of rich practical experience and professional knowledge engaged in the design and manufacture of this type of product, and cooperates with the application of theories, in order to create a new type of LED driver circuit. The light-emitting diode driving circuit can improve the generally existing light-emitting diode driving circuit to make it more practical. Through continuous research, design, and after repeated trial samples and improvements, the utility model with practical value is finally created.

Contents of the invention

The main purpose of the utility model is to overcome the defects existing in the existing light-emitting diode drive circuit and provide a new light-emitting diode drive circuit. The technical problem to be solved is to maintain the pulse width of the input power when the input power rises. In the range where the power factor can reach the standard value, it is very suitable for practical use.

The purpose of this utility model and the solution to its technical problems are achieved by adopting the following technical solutions. According to a light-emitting diode drive circuit proposed by the utility model, the drive circuit obtains input power from a power source to drive at least one light-emitting diode. The drive circuit includes: a power factor correction circuit connected to the power source and a switch unit , to obtain the input power and determine the timing of the input power flowing through the power factor correction circuit by turning on and off the switch unit; a power conversion unit, connected to the power factor correction circuit and the light emitting diode, to obtain the input power through the power factor correction circuit and Converted to an output power transmitted to the light-emitting diode; a pulse width modulation unit, connected to the power source and the switch unit, generates a pulse signal that turns on the switch unit, and is extracted from the input power passing through the power conversion unit A feedback signal determines the conduction time interval of the pulse signal; an impedance modulation unit is connected to the power source and the switch unit, and has at least two power paths with different impedances between the switch unit, and obtains a power path from the input power The voltage detection signal is used to determine the equivalent impedance value of the power path to adjust the magnitude of the feedback signal, so as to adjust the conduction time interval of the pulse signal and control the timing of the input power flowing through the power factor correction circuit.

The purpose of the utility model and the solution to its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned light-emitting diode drive circuit, the impedance modulation unit includes a first switch connected to the power source to obtain a voltage detection signal and output a trigger signal, and a switch unit connected to the first switch to obtain a trigger signal the second switch, and the second switch determines the power path between the power conversion unit and the second switch according to the trigger signal to adjust the magnitude of the feedback signal.

In the aforementioned LED driving circuit, a first resistor and a second resistor connected in parallel with the first resistor and the second switch are provided between the second switch and the power conversion unit.

The aforementioned light-emitting diode drive circuit, wherein the first switch is a metal-oxide-semiconductor field-effect transistor

In the aforementioned light-emitting diode driving circuit, the second switch is a metal-oxide-semiconductor field-effect transistor.

In the aforementioned light-emitting diode driving circuit, the switch unit is a metal-oxide-semiconductor field-effect transistor.

In the aforementioned LED driving circuit, the pulse width modulation unit is a power factor correction IC.

Compared with the prior art, the utility model has obvious advantages and beneficial effects. As can be seen from the above, in order to achieve the above object, the utility model provides a light emitting diode drive circuit, the drive circuit obtains an input power from a power source to drive at least one light emitting diode, which includes a power factor correction circuit, a power conversion unit . A pulse width modulation unit and an impedance modulation unit, wherein the power factor correction circuit is connected to the power source and a switch unit to obtain the input power and use the switch unit to determine the input power flowing through the power factor correction circuit Timing, and the power conversion unit obtains input power through the power factor correction circuit and converts it into an output power for driving a light emitting diode and outputs a feedback signal to the pulse width modulation unit, and the pulse width modulation unit generates a lead Pass the pulse signal of the switch unit, and use the feedback signal to determine the conduction time interval of the pulse signal. In addition, the impedance modulation unit is connected to the power source and the switch unit, and is set between the switch unit There are at least two power paths with different impedances, and a voltage detection signal is obtained from the input power to determine the equivalent impedance value of the power path to adjust the magnitude of the feedback signal, thereby controlling the conduction time of the pulse signal The time sequence of the input power being transmitted to the power conversion unit through the power factor correction circuit is adjusted so that when the input power rises, the pulse width of the input power is maintained in a range where the power factor can reach a standard value.

By virtue of the above technical solutions, the LED drive circuit of the present utility model has at least the following advantages and beneficial effects:

The utility model integrates the circuit from two levels to one level to complete the technical scheme. Compared with the existing known technology, the utility model has the beneficial effect of effectively reducing the power consumption and improving the output efficiency, and reducing the component parts to save production. cost.

In summary, the utility model is a light emitting diode driving circuit, which is connected to a power source to generate an output power to drive at least one light emitting diode, which includes a power factor correction circuit, a power conversion unit, a pulse width modulation unit and An impedance modulation unit, the pulse width modulation unit generates a pulse signal that turns on a switch unit to determine whether the switch unit is turned on or off, and the switch unit determines whether the input power flows through the power factor correction circuit and The timing sequence of the power conversion unit, wherein at least two power paths with different impedances are provided between the impedance modulation unit and the switch unit, and a voltage detection signal is obtained from the input power for the impedance modulation unit to switch The size of the feedback signal is adjusted in the power paths with different equivalent impedance values, so as to improve the lack of power factor reduction caused by the increase of the input power. The utility model has the above-mentioned many advantages and practical value, it has great improvement no matter in product structure or function, has significant progress in technology, and has produced easy-to-use and practical effect, and compared with existing light-emitting diode The driving circuit has enhanced outstanding functions, so it is more suitable for practical use, and it is a novel, progressive and practical new design.

The above description is only an overview of the technical solutions of the present utility model. In order to better understand the technical means of the present utility model, it can be implemented according to the contents of the description, and in order to make the above-mentioned and other purposes, features and advantages of the present utility model better. It is obvious and easy to understand. The preferred embodiments are specifically cited below, together with the accompanying drawings, and detailed descriptions are as follows.

Description of drawings

FIG. 1 is a schematic diagram of a traditional LED driving circuit.

Fig. 2 is a schematic block diagram of the utility model.

FIG. 3 is a schematic diagram of the circuit structure of the present invention.

Detailed ways

In order to further explain the technical means and effects of the utility model to achieve the intended purpose of the invention, the specific implementation, structure, characteristics and characteristics of the light-emitting diode drive circuit proposed according to the utility model will be described below in conjunction with the accompanying drawings and preferred embodiments. Its effect is described in detail below.

The aforementioned and other technical contents, features and effects of the present utility model will be clearly presented in the following detailed description of preferred embodiments with reference to the drawings. Through the description of the specific implementation, one can get a deeper and more specific understanding of the technical means and effects of the utility model to achieve the intended purpose, but the attached drawings are only for reference and description, and are not used to explain the present invention. Utility models are restricted.

Relevant detailed description and technical content of the utility model, now just explain as follows with respect to coordinating drawing:

Please refer to FIG. 2, the utility model is a light emitting diode drive circuit, the drive circuit is arranged between a power source 10 and at least one light emitting diode 30, which includes a power factor correction circuit 60, a power conversion unit 20 . A pulse width modulation unit 40 and an impedance modulation unit 50, wherein the power factor correction circuit 60 is connected to the power source 10 and the power conversion unit 20, and transmits the input power Vin of the power source 10 to the power conversion unit 20, and the power factor correction circuit 60 is further connected to a switch unit 70, and the timing of the input power Vin being transmitted to the power conversion unit 20 through the power factor correction circuit 60 is determined by the on and off of the switch unit 70, so that The power conversion unit 20 converts the input power Vin into an output power Vout for driving the light emitting diode 30; Pulse signal S2, and a feedback signal S1 is extracted from the input power Vin passing through the power conversion unit 20 to determine the conduction time interval of the pulse signal S2. In addition, the impedance modulation unit 50 is connected to the power source 10 and the switch unit 70, and there are at least two power paths with different impedances between the switch unit 70, and a voltage detection signal V1 is obtained from the input power Vin to determine the equivalent impedance value of the power path for adjustment The magnitude of the feedback signal S1 is used to adjust the conduction time interval of the pulse signal S2 and control the timing of the input power Vin flowing through the power factor correction circuit 60, thereby controlling the pulse width of the input power Vin so that the power factor reaches the standard The range of values constitutes the main structure of the utility model, so that the utility model can adjust its power factor according to the size of the input power Vin of the power source 10, and then meet the needs of the market.

Please also refer to FIG. 3 , which is a schematic diagram of the circuit structure of the present invention. In the embodiment of this figure, the impedance modulation unit 50 includes a first switch 51 connected to the power source 10 and a first switch connected to the first switch. 51. The switch unit 70 and the second switch 52 of the pulse width modulation unit 40, the switch unit 70, the first switch 51 and the second switch 52 are metal-oxide-semiconductor field-effect transistors (MOSFETs), and the first A first resistor R1 and a second resistor R2 connected in parallel with the first resistor R1 and the second switch 52 are arranged between the second switch 52 and the switch unit 70, and the pulse width modulation unit 40 is a power factor correction IC.

The circuit operation mode of the present utility model is as follows. Initially, when the input power Vin is at the first potential (such as 110V), the input power Vin is divided by a voltage divider circuit 80 to generate a voltage detection signal V1 to the first potential. switch 51, at this time, the first switch 51 is not yet turned on and outputs a high-level trigger signal V3 to the second switch 52 to make the second switch 52 turn on, and the first resistor R1 and the first resistor R1 The two resistors R2 are connected in parallel to each other to form a smaller equivalent impedance value, so that the power conversion unit 20 generates a larger feedback signal S1 (ie, the current flowing through the switch unit 70 ), so that the second switch 52 is in the second switch 52 A node connected in parallel between a resistor R1 and the second resistor R2 generates a relatively low-level control signal V2 and transmits it to the pulse-width modulation unit 40 , and the pulse-width modulation unit 40 is based on the level of the control signal V2 And the pulse signal S2 is output to the switch unit 70, so that the power factor of the driving circuit reaches a preset value (eg, 0.9).

When the input power Vin increases to a second potential (such as 180V or more than 180V), the pulse width of the input power Vin decreases as the potential of the input power Vin rises, resulting in a downward trend of the power factor. At this time, The voltage detection signal V1 generated by the input power Vin through the voltage divider circuit 80 also rises to turn on the first switch 51, and the first switch 51 outputs a low-level trigger signal V3 to the second switch 52 , so that the second switch 52 is turned off, so that the feedback signal S1 of the power conversion unit 20 only passes through the second resistor R2 (with a larger equivalent impedance value), and provides the pulse width modulation unit 40 A relatively high-level control signal V2, and the pulse width modulation unit 40 adjusts the conduction time interval of the pulse signal S2 according to the control signal V2, and transmits the pulse signal S2 to the switch unit 70, In order to control the timing when the input power Vin is transmitted to the power conversion unit 20 , the power factor is raised to a preset value.

In summary, the utility model mainly uses the impedance modulation unit 50 to adjust the impedance between the impedance modulation unit 50 and the switch unit 70 according to the magnitude of the input power Vin, so as to control the magnitude of the feedback signal of the power conversion unit 20 so that the pulse width modulation unit 40 controls the conduction time interval of the pulse signal S2 according to the feedback signal S1, and then controls the time interval during which the input power Vin is transmitted to the power conversion unit 20 through the power factor correction circuit 60, In order to control the pulse width of the input power Vin to maintain the range where the power factor can reach a standard value.

The above are only preferred embodiments of the present utility model, and do not limit the utility model in any form. Although the utility model has been disclosed as above with preferred embodiments, it is not intended to limit the utility model. Any Those skilled in the art can use the technical content disclosed above to make some changes or modify them into equivalent embodiments without departing from the technical solution of the present utility model. Content, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the utility model still belong to the scope of the technical solution of the utility model.

Claims (7)

1. A light emitting diode driving circuit, the driving circuit obtains an input power Vin of a power source (10) to drive at least one light emitting diode (30), it is characterized in that the driving circuit includes: A power factor correction circuit (60), which connects the power source (10) and a switch unit (70), to obtain the input power Vin and determine the input power Vin to flow through the power factor by turning on and off the switch unit (70) correcting the timing of the circuit (60); A power conversion unit (20), connected to the power factor correction circuit (60) and the light-emitting diode (30), obtains the input power Vin through the power factor correction circuit (60) and converts it into an output power Vout transmitted to the light-emitting diode (30) ; A pulse width modulation unit (40), connected to the power source (10) and the switch unit (70), generates a pulse signal S2 that turns on the switch unit (70), and generates a pulse signal S2 that passes through the power conversion unit (20). A feedback signal S1 is extracted from the input power Vin to determine the conduction time interval of the pulse signal S2; An impedance modulation unit (50), connected to the power source (10) and the switch unit (70), and having at least two power paths with different impedances between the switch unit (70), and obtaining a voltage from the input power Vin The detection signal V1 is used to determine the equivalent impedance value of the power path to adjust the magnitude of the feedback signal S1, thereby adjusting the conduction time interval of the pulse signal S2 and controlling the timing of the input power Vin flowing through the power factor correction circuit (60). 2. The light-emitting diode driving circuit according to claim 1, wherein the impedance modulation unit (50) includes a device connected to the power source (10) to obtain a voltage detection signal V1 and output a trigger signal V3 The first switch (51), and a second switch (52) that connects the switch unit (70) and the first switch (51) and obtains the trigger signal V3, and the second switch (52) determines the power according to the trigger signal V3 The power path between the conversion unit (20) and the second switch (52) is used to adjust the magnitude of the feedback signal S1. 3. The light-emitting diode driving circuit according to claim 2, wherein a first resistor (R1) is provided between the second switch (52) and the power conversion unit (20), and a resistor (R1) connected to the The first resistor (R1) and the second switch (52) are connected in parallel with the second resistor (R2). 4. The light emitting diode driving circuit according to claim 2, wherein the first switch (51) is a metal oxide half field effect transistor. 5. The LED driving circuit according to claim 2, wherein the second switch (52) is a metal oxide half field effect transistor. 6. The light emitting diode driving circuit according to claim 1, characterized in that said switch unit (70) is a metal oxide half field effect transistor. 7. The LED driving circuit according to claim 1, wherein the pulse width modulation unit (40) is a power factor correction integrated circuit.

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