CN107371299B - Linear constant-current LED driving circuit with high power factor and driving method - Google Patents
Linear constant-current LED driving circuit with high power factor and driving method Download PDFInfo
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- CN107371299B CN107371299B CN201710757941.3A CN201710757941A CN107371299B CN 107371299 B CN107371299 B CN 107371299B CN 201710757941 A CN201710757941 A CN 201710757941A CN 107371299 B CN107371299 B CN 107371299B
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- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
Abstract
The invention discloses a high-power factor linear constant-current LED driving circuit and a driving method, wherein the high-power factor linear constant-current LED driving circuit comprises a whole bridge input circuit, an LED string, a first MOS tube, a second MOS tube, a first resistor, a second resistor, a first amplifier, a second amplifier, a capacitor and an integrator.
Description
Technical Field
The invention relates to the field of LED driving circuits, in particular to a high-power-factor linear constant-current LED driving circuit and a driving method.
Background
The LED lamp has the advantages of low energy consumption, long service life, high light efficiency and the like, and is widely applied to the fields of illumination, decoration and the like. In order to reduce harmonic pollution to a power grid and improve an input side power factor, the application of a power factor correction technology in an LED lamp is also gradually popularized.
The LED driving circuit with the power factor correction function generally adopts a switching power supply driving technology or a piecewise linear constant current technology, the current precision is not high, the structure is complex, the cost is high, the LED driving circuit is not suitable for a low-cost low-power LED driving power supply, and the current LED circuit has the following two forms:
the first is an existing linear constant current LED driving circuit consisting of a rectifier bridge input circuit, LED strings, an amplifier, MOS tubes and sampling resistors. The circuit does not have a power factor correction function, and the LED instantaneous current is constantly equal to the reference voltage Vref/the sampling resistor RS.
The second is the existing piecewise linear constant current LED drive circuit with power factor correction function, the circuit includes rectifier bridge input circuit, LED string, constant current control circuit, MOS tube and sampling resistor, the way that this circuit realizes the power factor correction is: the LED lamp strings are conducted in a segmented mode along with the change of the input voltage, and when the input voltage is low, only part of the LED lamp strings are conducted; when the input voltage is higher, all LED lamp strings are conducted, so that the change of the input power along with the input alternating voltage is realized, the circuit has the defects of complex structure, more LED lamp beads are needed, and the utilization rate of the LED lamp beads is not high.
Disclosure of Invention
The invention solves the technical problem of providing a linear constant current LED driving circuit with simple circuit structure and low cost and high power factor.
The technical scheme adopted for solving the technical problems is as follows: the utility model provides a high power factor's linear constant current LED drive circuit, includes rectifier bridge input circuit and LED cluster, still includes first MOS pipe, second MOS pipe, first resistance, second resistance, first amplifier, second amplifier, electric capacity and integrator, rectifier bridge input circuit is connected with the LED cluster positive pole, the drain electrode of first MOS pipe is connected with the LED cluster negative pole, the one end of first resistance is connected with the source electrode of first MOS pipe and the input of integrator respectively, the other end ground of first resistance, the output of integrator is connected with the syntropy input of first amplifier, the reverse input of first amplifier is connected with reference voltage, the output of first amplifier is connected with the grid of second MOS pipe, the drain electrode of second MOS pipe is connected with the syntropy input of second amplifier and the one end of second resistance respectively, the source electrode of second MOS pipe is grounded, the other end of second resistance is connected with the output of LED cluster, the reverse input of second amplifier is connected with the input of integrator, the output of first end ground connection of electric capacity.
The invention also discloses a high-power factor linear constant current LED driving method, which comprises the steps of setting the reference voltage as Vref, the resistance value of the first resistor as RS, and the equivalent resistance value of the second MOS tube as R ON_N2 When the average current output by the LED string is larger than Vref/RS, the voltage value output by the integrator after collecting the average current is larger than Vref, so that the output voltage of the first amplifier is increased, and the equivalent of the second MOS tube is realizedResistance value R ON_N2 The average value of the voltage input into the non-inverting input end of the second amplifier is reduced after the voltage of the second MOS tube and the second resistor is divided, so that the average value of the voltage input into the grid electrode of the first MOS tube by the second amplifier is reduced, the average value of the on-resistance of the first MOS tube is increased, the average current output by the LED string is reduced, and when the system reaches stability through feedback, the average current of the LED is maintained at
Further is: the second MOS tube (4) works in a linear region and forms a voltage dividing resistor string with the second resistor (9), so that the voltage of the non-inverting input end of the second amplifier (7) changes along with the output voltage of the rectifier bridge, the LED instantaneous current changes along with the input alternating voltage, and the LED lamp string instantaneous current is in phase with a sinusoidal voltage signal after the rectifier bridge, namely the input power is in phase with the sinusoidal voltage signal.
The beneficial effects of the invention are as follows: the LED driving circuit of the invention enables the average value of the first voltage on the first resistor to be equal to the reference voltage value through closed loop feedback adjustment, so that the average current of the LED is maintained atMeanwhile, the LED instantaneous current changes along with the alternating-current input voltage, and the LED lamp string instantaneous current is in phase with the sinusoidal voltage signal after the rectifier bridge, namely the input power is in phase with the sinusoidal voltage signal, so that the driving circuit has a higher power factor.
Drawings
Fig. 1 is a schematic diagram of a linear constant current LED driving circuit with high power factor.
Fig. 2 is a timing diagram of a high power factor linear constant current LED drive.
Fig. 3 is a diagram of a conventional linear constant current LED driving circuit.
Fig. 4 is a diagram of a conventional piecewise linear constant current LED drive circuit.
Marked in the figure as: the LED light source comprises a rectifier bridge input circuit 1, an LED string 2, a first MOS tube 3, a second MOS tube 4, an integrator 5, a first amplifier 6, a second amplifier 7, a first resistor 8, a second resistor 9 and a capacitor 10.
Detailed Description
The invention is further described below with reference to the drawings and the detailed description.
The linear constant current LED driving circuit with high power factor as shown in fig. 1 comprises a rectifier bridge input circuit 1, an LED string 2, a first MOS tube 3, a second MOS tube 4, a first resistor 8, a second resistor 9, a first amplifier 6, a second amplifier 7, a capacitor 10 and an integrator 5, wherein the rectifier bridge input circuit 1 is connected with the positive electrode of the LED string 2, the drain electrode of the first MOS tube 3 is connected with the negative electrode of the LED string 2, one end of the first resistor 8 is respectively connected with the source electrode of the first MOS tube 3 and the input end of the integrator 5, the other end of the first resistor 8 is grounded, the output end of the integrator 5 is connected with the same-direction input end of the first amplifier 6, the reverse input end of the first amplifier 6 is connected with a reference voltage, the output end of the first amplifier 6 is connected with the gate electrode of the second MOS tube 4, the drain electrode of the second MOS tube 4 is respectively connected with the same-direction input end of the second amplifier 7 and one end of the second resistor 9, one end of the second MOS tube 4 is grounded, the other end of the second MOS tube 4 is connected with the other end of the capacitor 10, and the other end of the capacitor is connected with the other end of the capacitor 10.
The working principle is as follows: the first resistor 8 of the circuit is a sampling resistor, the voltage generated by the average current flowing through the LED lamp string on the sampling resistor RS is calculated by the integrator 5 to obtain an average value, the average value is input to the positive input end of the first amplifier 6 and is compared with the reference voltage input by the reverse end of the first amplifier 6, and calculated, when the voltage of the positive input end of the first amplifier 6 is larger than the reference voltage, the output voltage of the first amplifier 6 is increased, when the voltage of the positive input end of the first amplifier 6 is smaller than the reference voltage, the output voltage of the first amplifier 6 is reduced, the output voltage of the first amplifier 6 is used for controlling the second MOS tube 4, the second MOS tube 4 works in a linear region and is equivalent to a variable resistor, the equivalent resistance value of the variable resistor is controlled by the output voltage of the first amplifier 6, namely, when the output voltage of the first amplifier 6 is high,the equivalent resistance of the second MOS tube 4 is small, when the output voltage of the first amplifier 6 is low, the equivalent resistance of the second MOS tube 4 is large, the second MOS tube 4 and the second resistor 9 connected in series form a voltage dividing resistor structure, when the equivalent resistance of the second MOS tube 4 is small, the voltage of the homodromous input end of the second amplifier 7 is small, so that the grid voltage value of the first MOS tube 3 is reduced, the on resistance value of the first MOS tube 3 is increased, and the average current of the LED is gradually reduced to(reference voltage/first resistor 8) and stabilizes to +.>(reference voltage/first resistor 8), so that the setting of the above-mentioned circuit stabilizes the average current output by the LED to +.>Vref is a reference voltage value, and RS is a first resistor 8 value; according to the characteristics of the amplifier, the voltages of the non-inverting input terminal and the inverting input terminal of the first amplifier 6 are equal due to the negative feedback principle, so that the average current of the LED is not changed along with the alternating current output voltage and the LED voltage, and the average current of the LED output has higher precision. The capacitor 10 is used for stabilizing the gate voltage of the second MOS tube 4, after the system stably works, the gate voltage of the MOS tube 4 is basically maintained unchanged, and the equivalent resistance of the second MOS tube 4 is basically maintained unchanged, and the second resistor 9 and the second MOS tube 4 form a voltage dividing resistor, so that the voltage of the non-inverting input end of the second amplifier 7 changes along with the output voltage of the rectifier bridge, the instantaneous voltage generated by the instantaneous current flowing through the LED lamp string on the first resistor 8 changes along with the voltage of the non-inverting input end of the second amplifier 7, namely, the instantaneous current of the LED lamp string changes along with the input alternating voltage, and the input power changes along with the input alternating voltage, namely, the power factor correction function is realized.
Further explained is: let the reference voltage be Vref, the voltage of the first resistor 8 be RS, the equivalent resistance value of the second MOS tube 4 be R ON_N2 When the average current output by the LED string 2 is greater than Vref/RS, the integrator5 the output voltage value after collecting the average current is larger than Vref, so that the output voltage of the first amplifier 6 is increased, and the equivalent resistance value R of the second MOS tube 4 is increased ON_N2 The average value of the voltage input into the non-inverting input end of the second amplifier 7 after the voltage division of the second MOS tube 4 and the second resistor 9 is reduced, so that the average value of the voltage input into the grid electrode of the first MOS tube 3 by the second amplifier 7 is reduced, the average value of the on-resistance of the first MOS tube 3 is increased, and the average current output by the LED string 2 is reduced, thereby realizing closed-loop control.
Further explained is: the sinusoidal voltage of the rectifier bridge input circuit 1 can be denoted as V AC =1.414×vin×|sinwt|, where Vin is the ac mains active value, the voltage signal at the negative terminal of the LED string can be expressed as: v (V) LED- ＝V AC -V OUT Wherein VOUT is the voltage drop on the LED string, and the equivalent resistance R of the second resistor 9 and the second MOS tube 4 ON_N2 The voltage dividing resistor is configured to divide the voltage of the negative terminal of the LED lamp string, and the signal obtained after the division is connected to the non-inverting terminal input terminal of the second amplifier 7, where the voltage can be expressed as:instantaneous current I flowing through LED lamp string at any moment OUT The voltage generated on the first resistor 8, i.e. the sampling resistor RS, is equal to the voltage at the in-phase terminal of the second amplifier 7, i.e.: />The instantaneous current of the LED at any instant in time can be expressed as: />According to the above equation, the instantaneous current of the LED string is in phase with the sinusoidal voltage signal after the rectifier bridge, i.e. the input power is in phase with the sinusoidal voltage signal, so the LED driving circuit has a higher power factor.
Therefore, the invention has simple structure and low cost, and the average current output by the LED does not change along with the input voltage and the LED load voltage, has better adjustment rate, and is very suitable for low-cost low-power LED driving power supplies.
The invention also discloses a high-power factor linear constant current LED driving method, which comprises the steps of setting the reference voltage as Vref, the voltage of the first resistor 8 as RS and the equivalent resistance value of the second MOS tube 4 as R ON_N2 When the average current output by the LED string 2 is greater than Vref/RS, the voltage value output by the integrator 5 after collecting the average current is greater than Vref, so that the output voltage of the first amplifier 6 is increased, and the equivalent resistance value R of the second MOS tube 4 is increased ON_N2 The average value of the voltage input into the non-inverting input end of the second amplifier 7 after the voltage division between the second MOS tube 4 and the second resistor 9 is reduced, so that the average value of the voltage input into the grid electrode of the first MOS tube 3 by the second amplifier 7 is reduced, the average value of the on-resistance of the first MOS tube 3 is increased, the average current output by the LED string 2 is reduced, and when the system reaches stability through closed loop feedback, the average current output by the LED is maintained atMeanwhile, the instantaneous current of the LED lamp string is in phase with the sinusoidal voltage signal after the rectifier bridge, namely the input power is in phase with the sinusoidal voltage signal, so that the LED driving circuit has a higher power factor.
While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.
Claims (2)
1. The utility model provides a high power factor's linear constant current LED drive circuit, includes rectifier bridge input circuit (1) and LED cluster (2), its characterized in that: still include first MOS pipe (3), second MOS pipe (4), first resistance (8), second resistance (9), first amplifier (6), second amplifier (7), electric capacity (10) and integrator (5), rectifier bridge input circuit (1) is connected with LED cluster (2) anodal, the drain electrode of first MOS pipe (3) is connected with LED cluster (2) negative pole, first electricityOne end of the resistor (8) is respectively connected with a source electrode of the first MOS tube (3) and an input end of the integrator (5), the other end of the first resistor (8) is grounded, the output end of the integrator (5) is connected with a homodromous input end of the first amplifier (6), a reverse input end of the first amplifier (6) is connected with a reference voltage, the output end of the first amplifier (6) is connected with a grid electrode of the second MOS tube (4), a drain electrode of the second MOS tube (4) is respectively connected with the homodromous input end of the second amplifier (7) and one end of the second resistor (9), the source electrode of the second MOS tube (4) is grounded, the other end of the second resistor (9) is connected with the output end of the LED string (2), the reverse input end of the second amplifier (7) is connected with the input end of the integrator (5), one end of the capacitor (10) is connected with the output end of the first amplifier (6), and the other end of the capacitor (10) is grounded; setting the reference voltage as Vref, the resistance value of the first resistor (8) as RS, the equivalent resistance value of the second MOS tube (4) as RON_N2, when the average current output by the LED string (2) is larger than Vref/RS, the voltage value output by the integrator (5) after collecting the average current is larger than Vref, so that the output voltage of the first amplifier (6) is increased, the equivalent resistance value RON_N2 of the second MOS tube (4) is reduced, the average voltage value of the non-inverting input end of the second amplifier (7) is reduced after the voltage of the second MOS tube (4) and the second resistor (9) are divided, the average voltage value of the grid voltage input by the second amplifier (7) to the first MOS tube (3) is reduced, so that the on-resistance average value of the first MOS tube (3) is increased, the average current output by the LED string (2) is reduced, and when the system reaches stability through feedback, the average current of the LED is maintained at the same levelIn this way, the cycle is completed.
2. A high power factor linear constant current LED driving method comprising the high power factor linear constant current LED driving circuit of claim 1, characterized in that: the second MOS tube (4) works in a linear region and forms a voltage dividing resistor string with the second resistor (9), so that the voltage of the non-inverting input end of the second amplifier (7) changes along with the output voltage of the rectifier bridge, and the instantaneous current of the LED changes along with the input alternating voltage.
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| CN201710757941.3A CN107371299B (en) | 2017-08-29 | 2017-08-29 | Linear constant-current LED driving circuit with high power factor and driving method |
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| CN107371299B true CN107371299B (en) | 2023-09-19 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108024417B (en) * | 2017-12-22 | 2024-01-16 | 泉芯电子技术(深圳)有限公司 | High-voltage linear sectional type LED driving circuit |
| CN107979898A (en) * | 2017-12-27 | 2018-05-01 | 苏州菲达旭微电子有限公司 | Low-voltage LED linear drive circuit |
| US10219339B1 (en) * | 2018-02-19 | 2019-02-26 | Ixys, Llc | Current correction techniques for accurate high current short channel driver |
| CN110099478B (en) * | 2018-08-14 | 2022-03-22 | 上海迎好源科技有限公司 | Non-inductance step-down type LED driving circuit and method |
| CN110838789B (en) * | 2018-08-17 | 2021-06-04 | 美芯晟科技（北京）有限公司 | Ripple suppression circuit, system and method |
| CN114885456B (en) * | 2022-07-06 | 2022-09-30 | 季华实验室 | Magnetron filament control circuit |
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| US5614810A (en) * | 1994-02-14 | 1997-03-25 | Magneteck, Inc. | Power factor correction circuit |
| WO2002023694A2 (en) * | 2000-09-15 | 2002-03-21 | Artesyn Technologies, Inc. | Power factor correction control circuit and power supply including same |
| CN201742599U (en) * | 2010-05-12 | 2011-02-09 | 英飞特电子（杭州）有限公司 | High power factor constant current driving circuit |
| CN102244954A (en) * | 2010-05-12 | 2011-11-16 | 英飞特电子（杭州）有限公司 | Constant current drive circuit with high power factor |
| CN207150908U (en) * | 2017-08-29 | 2018-03-27 | 无锡麟力科技有限公司 | A kind of linear constant current LED drive circuit of High Power Factor |
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2017
- 2017-08-29 CN CN201710757941.3A patent/CN107371299B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5614810A (en) * | 1994-02-14 | 1997-03-25 | Magneteck, Inc. | Power factor correction circuit |
| WO2002023694A2 (en) * | 2000-09-15 | 2002-03-21 | Artesyn Technologies, Inc. | Power factor correction control circuit and power supply including same |
| CN201742599U (en) * | 2010-05-12 | 2011-02-09 | 英飞特电子（杭州）有限公司 | High power factor constant current driving circuit |
| CN102244954A (en) * | 2010-05-12 | 2011-11-16 | 英飞特电子（杭州）有限公司 | Constant current drive circuit with high power factor |
| CN207150908U (en) * | 2017-08-29 | 2018-03-27 | 无锡麟力科技有限公司 | A kind of linear constant current LED drive circuit of High Power Factor |
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