Linear LED drive circuit and drive method thereof
阅读说明：本技术 线性led驱动电路及其驱动方法 (Linear LED drive circuit and drive method thereof ) 是由 刘军 吴泉清 于 2019-03-01 设计创作，主要内容包括：本发明提供一种线性LED驱动电路及其驱动方法,包括：正极连接电压输入模块,负极连接第一恒流控制模块的第一LED灯段；输出端连接第一采样电阻第二端及第二采样电阻第一端的第一恒流控制模块；第一采样电阻的第二端与第二采样电阻串联,第一端接地；正极连接第一LED灯段的负极,负极经由第二恒流控制模块连接第二采样电阻第一端的第二LED灯段；第一二极管与第二二极管串联后与第一LED灯段并联；电容的一端连接第二二极管的负极,另一端经由第三恒流控制模块连接第二采样电阻的第一端。本发明可实现高功率因数、无频闪、低成本、高效率；且可兼容可控硅调光,适用范围广；在低输入电压时仍保持工作；同时,结构简单,易于实现。(The invention provides a linear LED drive circuit and a drive method thereof, wherein the drive method comprises the following steps: the anode of the first constant current control module is connected with the voltage input module, and the cathode of the first constant current control module is connected with the first LED lamp section of the first constant current control module; the output end of the first constant current control module is connected with the second end of the first sampling resistor and the first end of the second sampling resistor; the second end of the first sampling resistor is connected with the second sampling resistor in series, and the first end of the first sampling resistor is grounded; the anode is connected with the cathode of the first LED lamp section, and the cathode is connected with the second LED lamp section at the first end of the second sampling resistor through the second constant current control module; the first diode and the second diode are connected in series and then connected in parallel with the first LED lamp section; one end of the capacitor is connected with the cathode of the second diode, and the other end of the capacitor is connected with the first end of the second sampling resistor through the third constant current control module. The invention can realize high power factor, no stroboflash, low cost and high efficiency; the device is compatible with silicon controlled rectifier dimming and has wide application range; the operation is still kept at low input voltage; meanwhile, the structure is simple and easy to realize.)
1. A linear LED driving circuit, characterized in that the linear LED driving circuit comprises at least:
the LED lamp comprises a voltage input module, a first LED lamp section, a second LED lamp section, a first constant current control module, a second constant current control module, a third constant current control module, a first diode, a second diode, a first sampling resistor, a second sampling resistor and a capacitor;
the anode of the first LED lamp section is connected with the output end of the voltage input module, and the cathode of the first LED lamp section is connected with the first constant current control module;
the first constant-current control module comprises a first power switch tube and a first operational amplifier, the first power switch tube is connected between the negative electrode of the first LED lamp section and the first end of the first sampling resistor, the control end of the first power switch tube is connected with the output end of the first operational amplifier, and the input end of the first operational amplifier is respectively connected with the first end of the second sampling resistor and a first reference voltage; the second end of the first sampling resistor is grounded, and the second end of the second sampling resistor is connected with the first end of the first sampling resistor;
the anode of the second LED lamp section is connected with the cathode of the first LED lamp section, and the cathode of the second LED lamp section is connected with the first end of the second sampling resistor through the second constant-current control module;
the cathode of the first diode is connected with the anode of the first LED lamp section, the anode of the first diode is connected with the cathode of the second diode, and the anode of the second diode is connected with the cathode of the first LED lamp section;
one end of the capacitor is connected with the cathode of the second diode, and the other end of the capacitor is connected with the first end of the second sampling resistor through the third constant current control module.
2. The linear LED driving circuit of claim 1, wherein: the conducting voltage of the first LED lamp section is not more than half of the average value of the output voltage of the voltage input module.
3. The linear LED driving circuit according to claim 1 or 2, wherein: the number of the lamp beads of the first LED lamp section is larger than that of the lamp beads of the second LED lamp section.
4. The linear LED driving circuit of claim 3, wherein: the lamp bead quantity ratio of the first LED lamp section to the second LED lamp section comprises 2: 1.
5. the linear LED driving circuit according to claim 1 or 2, wherein: the second constant-current control module comprises a second power switch tube and a second operational amplifier; the second power switch tube is connected between the negative electrode of the second LED lamp section and the first end of the second sampling resistor, and the control end of the second power switch tube is connected with the output end of the second operational amplifier; and the input end of the second operational amplifier is respectively connected with the first end of the second sampling resistor and the second reference voltage.
6. The linear LED driving circuit according to claim 1 or 2, wherein: the third constant-current control module comprises a third power switch tube, a third operational amplifier, a third diode and a fourth diode; the third power switch tube is connected between the capacitor and the anode of the third diode, and the control end of the third power switch tube is connected with the output end of the third operational amplifier; the input end of the third operational amplifier is respectively connected with the cathode of the third diode and a third reference voltage; the cathode of the third diode is connected with the first end of the second sampling resistor; the anode of the fourth diode is grounded, and the cathode of the fourth diode is connected with the anode of the third diode.
7. The linear LED driving circuit according to claim 1 or 2, wherein: the linear LED driving circuit further comprises a reference voltage generating module, and the reference voltage generating module is used for providing reference voltage for the linear LED driving circuit.
8. The linear LED driving circuit of claim 7, wherein: the reference voltage generation module is further connected with a voltage detection module, the voltage detection module detects the input voltage, and the reference voltage generation module adjusts each reference voltage based on a detection signal of the voltage detection module so as to realize constant input power.
9. The linear LED driving circuit according to claim 1 or 2, wherein: the linear LED driving circuit further comprises a discharge current control module, wherein the discharge current control module is connected with the output end of the voltage input module and the first end of the second sampling resistor and is used for enabling the current flowing through the controllable silicon to be larger than or equal to the holding current of the controllable silicon.
10. The linear LED driving circuit of claim 9, wherein: the discharge current control module comprises a fifth diode, a fourth power switch tube, a sampling unit, a fourth operational amplifier and a current detection unit; the anode of the fifth diode is connected with the output end of the voltage input module, and the cathode of the fifth diode is connected with the anode of the first LED lamp section; the fourth power switch tube is connected between the output end of the voltage input module and one end of the sampling unit, and the control end of the fourth power switch tube is connected with the output end of the fourth operational amplifier; one end of the sampling unit is grounded; the current detection unit is connected with the sampling unit and the second sampling resistor and sums the currents flowing through the sampling unit and the LED lamp sections; the input end of the fourth operational amplifier is respectively connected with the current detection unit and the discharge threshold voltage, and the discharge current flowing through the sampling unit is adjusted based on the output current of the voltage input module.
11. A method according to any one of claims 1 to 10, wherein the method for driving the linear LED driving circuit at least comprises:
when the input voltage is greater than the conduction voltage of the first LED lamp section and less than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section, performing constant current control on the current flowing through the first LED lamp section based on a first constant current control module;
when the input voltage is greater than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section and is less than the sum of the conduction voltage of the first LED lamp section and the voltage at two ends of a capacitor, performing constant current control on the current flowing through the first LED lamp section and the second LED lamp section based on a second constant current control module;
when the input voltage is larger than the sum of the conducting voltage of the first LED lamp section and the voltage at two ends of the capacitor, the current flowing through the first LED lamp section is subjected to constant current control based on a third constant current control module, and the capacitor is charged by the input voltage;
when the input voltage is less than the voltage across the capacitor, the capacitor begins to discharge; when the input voltage is greater than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section, performing constant current control on the current flowing through the first LED lamp section and the second LED lamp section based on the second constant current control module; and when the input voltage is smaller than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section and is greater than the conduction voltage of the first LED lamp section, performing constant current control on the current flowing through the first LED lamp section based on the first constant current control module.
12. The driving method of a linear LED driving circuit according to claim 11, wherein: and adjusting the ratio of the first sampling resistor and the second sampling resistor to ensure that the output power is constant.
13. The driving method of a linear LED driving circuit according to claim 12, wherein: the output power of the linear LED driving circuit satisfies the following relational expression:
Vref1*VLED1/Rs1＝Vref2*(VLED1+VLED2)/(Rs1+Rs2)＝Vref3*VLED1/(Rs1+Rs2)
VLED1 is a conduction voltage of the first LED segment, VLED2 is a conduction voltage of the second LED segment, Vref1 is a first reference voltage, Vref2 is a second reference voltage, Vref3 is a third reference voltage, Rs1 is a resistance value of the first sampling resistor, and Rs2 is a resistance value of the second sampling resistor.
14. The method of driving a linear LED driving circuit according to any one of claims 11 to 13, wherein: and detecting the positive voltage of the first LED lamp section, and reducing the reference voltage of each constant current control module when the positive voltage of the first LED lamp section is greater than a set voltage.
15. The method of driving a linear LED driving circuit according to any one of claims 11 to 13, wherein: and detecting the output current of the voltage input module, and increasing a discharge path when the output current of the voltage input module is smaller than the holding current of the controllable silicon, so that the current flowing through the controllable silicon is larger than or equal to the holding current of the controllable silicon.
Technical Field
The invention relates to the field of integrated circuit design, in particular to a linear LED driving circuit and a driving method thereof.
Background
An LED is a semiconductor electronic component capable of emitting light, which can emit only low-intensity red light at an early stage, and with the continuous progress of technology, the light intensity has been improved to such an extent that visible light, infrared light and ultraviolet light are emitted. LEDs have the advantages of high efficiency, long life, low susceptibility to damage, high switching speed, high reliability, and the like, which are beyond the reach of conventional light sources, and have been widely used in indicator lights, displays, and lighting applications.
Generally, the overall efficiency in single-segment linear LED driving is determined by the LED on-voltage and the input voltage, and satisfies the following relationship:
as shown in fig. 1, in a linear LED driving scheme, in order to obtain a high Power Factor (PF), an electroless single-
In order to filter the power frequency flicker and improve the efficiency, an electrolytic capacitor needs to be added to the input, as shown in fig. 2, an improved linear
The two performances of high power factor and no stroboflash in the existing linear LED driving scheme are a pair of spears, and cannot be perfectly solved.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a linear LED driving circuit and a driving method thereof, which are used to solve the problem that high power factor and no strobe cannot be compatible in the prior art.
To achieve the above and other related objects, the present invention provides a linear LED driving circuit, comprising:
the LED lamp comprises a voltage input module, a first LED lamp section, a second LED lamp section, a first constant current control module, a second constant current control module, a third constant current control module, a first diode, a second diode, a first sampling resistor, a second sampling resistor and a capacitor;
the anode of the first LED lamp section is connected with the output end of the voltage input module, and the cathode of the first LED lamp section is connected with the first constant current control module;
the first constant-current control module comprises a first power switch tube and a first operational amplifier, the first power switch tube is connected between the negative electrode of the first LED lamp section and the first end of the first sampling resistor, the control end of the first power switch tube is connected with the output end of the first operational amplifier, and the input end of the first operational amplifier is respectively connected with the first end of the second sampling resistor and a first reference voltage; the second end of the first sampling resistor is grounded, and the second end of the second sampling resistor is connected with the first end of the first sampling resistor;
the anode of the second LED lamp section is connected with the cathode of the first LED lamp section, and the cathode of the second LED lamp section is connected with the first end of the second sampling resistor through the second constant-current control module;
the cathode of the first diode is connected with the anode of the first LED lamp section, the anode of the first diode is connected with the cathode of the second diode, and the anode of the second diode is connected with the cathode of the first LED lamp section;
one end of the capacitor is connected with the cathode of the second diode, and the other end of the capacitor is connected with the first end of the second sampling resistor through the third constant current control module.
Optionally, the turn-on voltage of the first LED lamp segment is not greater than half of the average value of the output voltage of the voltage input module.
More optionally, the number of the lamp beads of the first LED lamp segment is greater than the number of the lamp beads of the second LED lamp segment.
More optionally, the ratio of the number of the lamp beads of the first LED lamp segment to the number of the lamp beads of the second LED lamp segment includes 2: 1.
more optionally, the second constant current control module includes a second power switch tube and a second operational amplifier; the second power switch tube is connected between the negative electrode of the second LED lamp section and the first end of the second sampling resistor, and the control end of the second power switch tube is connected with the output end of the second operational amplifier; and the input end of the second operational amplifier is respectively connected with the first end of the second sampling resistor and the second reference voltage.
More optionally, the third constant current control module includes a third power switch tube, a third operational amplifier, a third diode, and a fourth diode; the third power switch tube is connected between the capacitor and the anode of the third diode, and the control end of the third power switch tube is connected with the output end of the third operational amplifier; the input end of the third operational amplifier is respectively connected with the cathode of the third diode and a third reference voltage; the cathode of the third diode is connected with the first end of the second sampling resistor; the anode of the fourth diode is grounded, and the cathode of the fourth diode is connected with the anode of the third diode.
More optionally, the linear LED driving circuit further includes a reference voltage generating module, and the reference voltage generating module is configured to provide a reference voltage for the linear LED driving circuit.
More optionally, the reference voltage generation module is further connected to a voltage detection module, the voltage detection module detects the input voltage, and the reference voltage generation module adjusts each reference voltage based on a detection signal of the voltage detection module to achieve constant input power.
More optionally, the linear LED driving circuit further includes a discharging current control module, and the discharging current control module is connected to the output terminal of the voltage input module and the first terminal of the second sampling resistor, and is configured to enable a current flowing through the thyristor to be greater than or equal to a holding current of the thyristor.
More optionally, the bleed-off current control module includes a fifth diode, a fourth power switch tube, a sampling unit, a fourth operational amplifier, and a current detection unit; the anode of the fifth diode is connected with the output end of the voltage input module, and the cathode of the fifth diode is connected with the anode of the first LED lamp section; the fourth power switch tube is connected between the output end of the voltage input module and one end of the sampling unit, and the control end of the fourth power switch tube is connected with the output end of the fourth operational amplifier; one end of the sampling unit is grounded; the current detection unit is connected with the sampling unit and the second sampling resistor and sums the currents flowing through the sampling unit and the LED lamp sections; the input end of the fourth operational amplifier is respectively connected with the current detection unit and the discharge threshold voltage, and the discharge current flowing through the sampling unit is adjusted based on the output current of the voltage input module.
To achieve the above and other related objects, the present invention provides a driving method of the linear LED driving circuit, including at least:
when the input voltage is greater than the conduction voltage of the first LED lamp section and less than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section, performing constant current control on the current flowing through the first LED lamp section based on a first constant current control module;
when the input voltage is greater than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section and is less than the sum of the conduction voltage of the first LED lamp section and the voltage at two ends of a capacitor, performing constant current control on the current flowing through the first LED lamp section and the second LED lamp section based on a second constant current control module;
when the input voltage is larger than the sum of the conducting voltage of the first LED lamp section and the voltage at two ends of the capacitor, the current flowing through the first LED lamp section is subjected to constant current control based on a third constant current control module, and the capacitor is charged by the input voltage;
when the input voltage is less than the voltage across the capacitor, the capacitor begins to discharge; when the input voltage is greater than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section, performing constant current control on the current flowing through the first LED lamp section and the second LED lamp section based on the second constant current control module; and when the input voltage is smaller than the sum of the conduction voltages of the first LED lamp section and the second LED lamp section and is greater than the conduction voltage of the first LED lamp section, performing constant current control on the current flowing through the first LED lamp section based on the first constant current control module.
Optionally, a ratio of the first sampling resistor and the second sampling resistor is adjusted so that the output power is constant.
More optionally, the output power of the linear LED driving circuit satisfies the following relation:
vref1 × VLED1/Rs1 ═ Vref2 (VLED1+ VLED2)/(Rs1+ Rs2) ═ Vref3 × VLED1/(Rs1+ Rs2), where VLED1 is the on-voltage of the first LED segment, VLED2 is the on-voltage of the second LED segment, Vref1 is the first reference voltage, Vref2 is the second reference voltage, Vref3 is the third reference voltage, Rs1 is the resistance value of the first sampling resistor, and Rs2 is the resistance value of the second sampling resistor.
More optionally, the positive voltage of the first LED lamp segment is detected, and the reference voltage of each constant current control module is reduced when the positive voltage of the first LED lamp segment is greater than a set voltage.
More optionally, the output current of the voltage input module is detected, and when the output current of the voltage input module is smaller than the holding current of the thyristor, the bleeding path is increased, so that the current flowing through the thyristor is greater than or equal to the holding current of the thyristor.
As described above, the linear LED driving circuit and the driving method thereof according to the present invention have the following advantageous effects:
1. the linear LED driving circuit and the driving method thereof have the advantages that the conduction time of the input voltage is longer, stroboflash is removed based on constant power output, and the consideration of high power factor and no stroboflash can be realized.
2. According to the linear LED driving circuit and the driving method thereof, the using number of the LED lamp beads is reduced through a specific framework, the voltage loss of the power switch tube at high voltage is reduced through capacitor charging, and the cost and the efficiency can be considered.
3. The linear LED driving circuit and the driving method thereof can be compatible with silicon controlled rectifier dimming, and have wide application range.
4. The linear LED driving circuit and the driving method thereof can still work at low input voltage through the energy storage of the capacitor.
5. The linear LED driving circuit and the driving method thereof have simple structure and are easy to realize.
Drawings
Fig. 1 is a schematic diagram of a non-electrolytic single-stage driving structure in the prior art.
Fig. 2 shows a schematic diagram of an improved linear LED driving circuit in the prior art.
Fig. 3 is a schematic diagram of a linear LED driving circuit according to the present invention.
Fig. 4 is a schematic diagram showing the waveform configuration of each node of the linear LED driving circuit according to the present invention.
Fig. 5 is a schematic diagram illustrating the operation of the linear LED driving circuit of the present invention when the circuit is powered by ac voltage.
Fig. 6 is a schematic diagram illustrating the operation principle of the linear LED driving circuit of the present invention when the capacitor is discharged.
Fig. 7 is a schematic diagram of another structure of the linear LED driving circuit according to the present invention.
Fig. 8 is a schematic diagram of another linear LED driving circuit according to the present invention.
Fig. 9 is a schematic diagram of another linear LED driving circuit according to the present invention.
Description of the element reference numerals
1 non-electrolysis single-stage driving structure
11 rectifier bridge
12 constant current control chip
2 linear LED driving circuit
21 power supply input module
22 LED lamp string
23 constant current control chip
3 linear LED driving circuit
31 voltage input module
311 silicon controlled rectifier
32 first constant current control module
33 second constant current control module
34 third constant current control module
35 reference voltage generating module
351 reference voltage generating unit
36 working voltage generating module
37 voltage detection module
38 digital filtering module
39 discharge current control module
391 sampling unit
392 current detection unit
393 threshold voltage generating unit
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 3 to fig. 9. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
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