CN109587891B - High-efficiency linear LED driving circuit - Google Patents
High-efficiency linear LED driving circuit Download PDFInfo
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- CN109587891B CN109587891B CN201811635050.1A CN201811635050A CN109587891B CN 109587891 B CN109587891 B CN 109587891B CN 201811635050 A CN201811635050 A CN 201811635050A CN 109587891 B CN109587891 B CN 109587891B
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- 230000001105 regulatory effect Effects 0.000 claims abstract description 39
- 230000001276 controlling effect Effects 0.000 claims abstract description 11
- 239000003990 capacitor Substances 0.000 claims description 38
- 238000007599 discharging Methods 0.000 claims description 20
- 238000005070 sampling Methods 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 8
- 238000013459 approach Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 6
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- 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]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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Abstract
The invention discloses a high-efficiency linear LED driving circuit, which comprises a linear regulating tube and a control circuit, wherein an alternating current input power supply is rectified by a rectifying circuit to obtain input voltage, the linear regulating tube is connected with an LED load in series, the input voltage supplies power to the LED load, the control circuit is connected with the control end of the linear regulating tube, the control circuit is used for controlling the current flowing through the linear regulating tube, a first working area, a second working area and a third working area are sequentially arranged in a half power frequency period, the current flowing through the linear regulating tube in the first working area is a first current, the current flowing through the linear regulating tube in the second working area is a second current, the current flowing through the linear regulating tube in the third working area is a third current, the change trend of the second current is opposite to that of the corresponding input voltage, and the second current reaches the lowest point at the peak value of the input voltage.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a high-efficiency linear LED driving circuit.
Background
The linear LED driving circuit in the prior art comprises a rectifying circuit, a linear regulating tube and a control circuit for controlling the linear regulating tube. The control circuit performs error processing on the current flowing through the linear regulation tube and the corresponding average current reference value through sampling so as to control the state of the linear regulation tube, thereby realizing output constant current.
The voltage VIN, the voltage VLED across the LED and the output current waveform are shown in fig. 1, and the voltage difference between the voltage VIN and the voltage VLED across the LED load is greater as the voltage VIN is closer to the peak position of the voltage VIN waveform in the power frequency period. The power consumption on the linear regulator M01 is (VIN-VLED) ×iout, i.e., the greater the voltage VIN is than the voltage VLED across the LED, the greater the power consumption on the linear regulator M01, the lower the system efficiency.
In the prior art, the linear LED driving circuit has low efficiency, so that the linear LED driving circuit is less applied to dimming applications, and the linear LED driving circuit is used as the LED dimming driving circuit by adopting a switching power supply. However, the cost of switching power supplies is higher than linear drive circuits, and schemes to increase the efficiency of linear LED drive circuits to accommodate dimming applications are being sought.
Disclosure of Invention
In view of the above, the present invention is directed to provide a high-efficiency linear LED driving circuit for reducing power consumption of a linear adjusting tube and realizing dimming, which is used for solving the technical problems of the prior art that the power consumption of the linear adjusting tube is large and the linear adjusting tube is difficult to be applied to dimming application.
The technical scheme of the invention is that the high-efficiency linear LED driving circuit with the following structure comprises a linear regulating tube and a control circuit, wherein an alternating current input power supply is rectified by a rectifying circuit to obtain input voltage, the linear regulating tube is connected with an LED load in series, the input voltage supplies power to the LED load, and the control circuit is connected with a control end of the linear regulating tube;
The control circuit is used for controlling the current flowing through the linear regulating tube, a first working area, a second working area and a third working area are sequentially arranged in a half power frequency period, the current flowing through the linear regulating tube in the first working area is a first current, the current flowing through the linear regulating tube in the second working area is a second current, the current flowing through the linear regulating tube in the third working area is a third current, the first current is equal to the third current, the change trend of the second current is opposite to that of the corresponding input voltage, and the second current reaches the lowest point at the peak value of the input voltage.
Optionally, the current flowing through the linear regulation tube is sampled to obtain a first voltage sampling signal representing the output current, error compensation processing is performed on the first voltage sampling signal and a variable average current reference signal to obtain an average current control signal, and the duration of at least one of the first working area, the second working area and the third working area or at least one current value of the first current, the second current and the third current is regulated according to the average current control signal, so that the average output current of the LED driving circuit approaches to the output current represented by the variable average current reference signal.
Optionally, the variable average current reference signal is adjusted according to the dimming signal to adjust the average output current through the load.
Optionally, the dimming signal is a PWM dimming signal or an analog dimming signal, and when the dimming signal is a PWM dimming signal, the PWM dimming signal is converted into an analog voltage, and the variable average current reference signal is adjusted according to the analog voltage; when the dimming signal is an analog dimming signal, the variable average current reference signal is adjusted according to the analog dimming signal.
Optionally, the control circuit includes a first operational amplifier, a first input terminal of the first operational amplifier receives the first voltage sampling signal, and a second input terminal of the first operational amplifier receives an instantaneous current reference signal.
Optionally, the control circuit further includes a reference signal generating circuit, configured to generate the instantaneous current reference signal, where the reference signal generating circuit includes a first capacitor, a charging current source and a discharging current source, where the charging current source and the discharging current source are both connected to the first capacitor, and the charging current source and the discharging current source are controlled to charge and discharge the first capacitor to adjust a voltage on the first capacitor, and the voltage on the first capacitor is used as the instantaneous current reference signal.
Optionally, the reference signal generating circuit further includes a first comparator, a first input end of the first comparator is connected with the first capacitor, a second input end of the first comparator receives a first reference voltage, the first reference signal characterizes expected values of the first current and the second current, and an output signal of the first comparator is used for controlling the charging current source to stop charging when the first capacitor voltage reaches the first reference voltage.
Optionally, in the second working area, the first phase and the second phase are included, in the first phase, the discharging current source starts to discharge the first capacitor, at this time, the charging current source does not charge the first capacitor, at the peak time of the input voltage, the second current reaches the lowest point, the first phase ends, in the second phase, the discharging current source stops discharging, the charging current source starts to charge the first capacitor, and when the first capacitor voltage reaches the first reference voltage, the charging current source stops charging, and the second phase ends.
Optionally, the reference signal generating circuit further includes a peak detection circuit, and the peak detection circuit is connected to a high potential end of the input voltage and is used for detecting a peak time of the input voltage.
Optionally, the peak detection circuit detects a peak time of the input voltage by detecting a rate of change of the input voltage.
Compared with the prior art, the invention has the following advantages: the invention sets three working areas, the first current of the first working area is equal to the third current of the third working area, the current of the second working area and the input voltage are in opposite change trend, the adjustment of average current can be realized, and the adjustment of variable average current reference signal can be realized by PWM signal or analog dimming signal, so as to realize dimming. The invention reduces the power consumption of the linear regulating tube, improves the system efficiency, and realizes PWM dimming and analog dimming based on the high-efficiency linear LED driving circuit.
Drawings
FIG. 1 is a waveform diagram illustrating the operation of a prior art LED driver circuit;
FIG. 2 is a schematic block diagram of a high efficiency linear LED of the present invention;
FIG. 3 is a waveform diagram illustrating the operation of a high efficiency linear LED of the present invention;
FIG. 4 is a schematic diagram of a reference signal generating circuit;
FIG. 5 is a circuit configuration diagram of a peak detection circuit;
Fig. 6 is a schematic diagram of the relationship between the dimming signal and the variable average current reference signal.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments only. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention.
In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate and clearly illustrate the embodiments of the present invention.
The basic implementation scheme of the invention is as follows: the LED driving circuit comprises a linear regulating tube and a control circuit, wherein an alternating current input power supply is rectified by a rectifying circuit to obtain input voltage, the linear regulating tube is connected with an LED load in series, the input voltage supplies power to the LED load, and the control circuit is connected with a control end of the linear regulating tube;
The control circuit is used for controlling the current flowing through the linear regulating tube, a first working area, a second working area and a third working area are sequentially arranged in a half power frequency period, the current flowing through the linear regulating tube in the first working area is a first current, the current flowing through the linear regulating tube in the second working area is a second current, the current flowing through the linear regulating tube in the third working area is a third current, the first current is equal to the third current, the change trend of the second current is opposite to that of the corresponding input voltage, and the second current reaches the lowest point at the peak value of the input voltage.
Based on the basic implementation scheme, the detailed description is given by adopting specific embodiments.
Referring to fig. 2, a principle structure of a high-efficiency linear LED driving circuit is illustrated. The sampling resistor R01 samples the output current, and when the input voltage VIN (obtained by rectifying an ac input power supply through a rectifier bridge) is greater than the LED load voltage VLED, the current starts to flow through the LED load and starts to enter the first operating region. The instantaneous value of the sampling resistor voltage VS (i.e. the first voltage sampling signal) is equal to the instantaneous current reference signal VREF, i.e. the current flowing through the LED load and the linear regulator tube M01 follows said instantaneous current reference signal VREF. The control circuit comprises a first operational amplifier U12, wherein a first input end of the first operational amplifier U12 receives the first voltage sampling signal VS, and a second input end of the first operational amplifier U12 receives an instantaneous current reference signal VREF.
The high efficiency linear LED driving circuit of the present invention can also control and regulate the average current through the LED load. And sampling the current flowing through the linear regulating tube to obtain a first voltage sampling signal VS representing the output current, carrying out error compensation processing on the first voltage sampling signal VS and a variable average current reference signal VAVE to obtain an average current control signal VC, and regulating the duration of at least one working area of the first working area, the second working area and the third working area or regulating the current value of at least one of the first current, the second current and the third current according to the average current control signal VC so as to enable the average output current of the LED driving circuit to approach the output current value represented by the variable average current reference signal VAVE. The error compensation processing is realized by an error compensation circuit, the error compensation circuit comprises a second operational amplifier U11 and a compensation capacitor C2, and the compensation capacitor C2 is connected to the output end of the second operational amplifier U11. The two inputs of the second operational amplifier U11 receive the first voltage sampling signal VS and the variable average current reference signal VAVE, respectively. The adjusting the duration of at least one of the first working area, the second working area and the third working area may be specifically implemented as: the moment at which the first operating region ends is controlled and regulated in accordance with the average current control signal VC to initiate discharge and into the second operating region, but is not limited to this manner. The specific implementation of adjusting at least one current value of the first current, the second current and the third current may be: the first current and the third current are adjusted according to the average current control signal VC, thereby changing the second current accordingly, but is not limited to this way.
Referring to fig. 3, an operational waveform of the high efficiency linear LED driving circuit is illustrated. In the figure, T represents the whole current interval, and a first operating region T1, a second operating region T2, and a third operating region T3 are provided. In the first operating region t1 and the third operating region t3, the instantaneous current reference signal VREF is kept stable, and the first current is equal to the third current. In the second operating region t2, the instantaneous current reference signal VREF is lowered, and at the peak position of the input voltage, the instantaneous current reference signal VREF reaches the minimum value, and then is increased to the third current.
Referring to fig. 4, a specific structure of the reference signal generating circuit is illustrated. The reference signal generating circuit comprises a first capacitor C1, a charging current source I1 and a discharging current source I2, wherein the charging current source I1 and the discharging current source I2 are connected with the first capacitor C1, the voltage on the first capacitor C1 is regulated by controlling the charging current source I1 and the discharging current source I2 to charge and discharge the first capacitor C1, and the voltage on the first capacitor C1 is used as an instantaneous current reference signal. The reference signal generating circuit comprises a first comparator U13, a first input end of the first comparator U13 is connected with the first capacitor C1, a second input end of the first comparator U13 receives a first reference voltage VREF1, the first reference signal VREF1 represents expected values of the first current and the second current, and an output signal of the first comparator U13 is used for controlling a charging current source to stop charging when the voltage of the first capacitor C1 reaches the first reference voltage VREF 1. For the control of the charge current source I1 and the discharge current source I2, whether it is switched in or not can be controlled by a switch, whether it is enabled or not can be controlled by the control signal, and its size can be adjusted by the control signal. In fig. 4, switches K1 and K2 are used to control whether the charging current source I1 and the discharging current source I2 are connected respectively, the input end of the first comparator U13 is connected with the switch K1, the peak time signal tp is connected with the switch K2, and the switch K1 and the switch K2 are controlled by other signals.
In the second working area, the first phase and the second phase are included, in the first phase, the discharging current source starts to discharge the first capacitor C1, at this time, the charging current source I1 does not charge the first capacitor C1, at the peak time of the input voltage VIN, the second current reaches the lowest point, the first phase ends, in the second phase, the discharging current source I2 stops discharging, the charging current source I1 starts to charge the first capacitor C1, and when the first capacitor voltage reaches the first reference voltage, the charging current source I1 stops charging, and the second phase ends.
Referring to fig. 5, a specific structure of the peak detection circuit is illustrated. The peak detection circuit samples the input voltage VIN, and the specific sampling can be realized by a voltage dividing circuit in the figure, wherein the voltage dividing circuit comprises resistors R02 and R03, the resistors R02 and R03 are connected in series, and the voltage at the common terminal of the two resistors represents the input voltage VIN. The common terminal of the resistors R02 and R03 is connected to a differentiating circuit, the differentiating circuit is used for detecting the change rate of the input voltage VIN, the differentiating circuit includes a second capacitor C3 and a resistor R04, the second capacitor C3 and the resistor R04 are connected in series, the voltage of the common terminal of the two represents the change rate of the input voltage VIN, the change rate of the input voltage VIN is compared with a reference signal VREF2, in general, the change rate of the voltage at the peak of the input voltage VIN is zero, the reference signal VREF2 can be set to a value close to zero, and of course, practical situations of an application scheme, such as setting of a reference ground, and the like, need to be considered. When the voltage at the common end of the second capacitor C3 and the resistor R04 reaches the reference signal VREF2, the output signal tp of the second comparator U14 is inverted, tp is used as a peak detection signal, and the signal is used for controlling the switch K2 to be turned off so as to stop discharging.
Referring to fig. 6, the relationship of the dimming signal and the variable average current reference signal is illustrated. The variable average current reference signal is adjusted according to the dimming signal to adjust the average output current through the load. The dimming signal is a PWM dimming signal or an analog dimming signal, when the dimming signal is a PWM dimming signal, the PWM dimming signal is converted into an analog voltage, and the variable average current reference signal is regulated according to the analog voltage; when the dimming signal is an analog dimming signal, the variable average current reference signal is adjusted according to the analog dimming signal. Fig. 6 illustrates that, taking a PWM dimming signal as an example, the analog voltage may be directly used as a variable average current reference signal, "the variable average current reference signal is adjusted according to the analog voltage," the scaling factor may be considered to be 1, or the variable average current reference signal may be obtained by scaling.
Although the embodiments have been described and illustrated separately above, and with respect to a partially common technique, it will be apparent to those skilled in the art that alternate and integration may be made between embodiments, with reference to one embodiment not explicitly described, and reference may be made to another embodiment described.
The above-described embodiments do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present invention.
Claims (8)
1. The utility model provides a high-efficient linear LED drive circuit, includes linear regulation pipe and control circuit, obtains input voltage after alternating current input power supply rectifies through rectifier circuit, linear regulation pipe is established ties with the LED load, input voltage supply to the LED load, control circuit with the control end of linear regulation pipe is connected, its characterized in that:
The control circuit is used for controlling the current flowing through the linear regulating tube, a first working area, a second working area and a third working area are sequentially arranged in a half power frequency period, the current flowing through the linear regulating tube in the first working area is a first current, the current flowing through the linear regulating tube in the second working area is a second current, the current flowing through the linear regulating tube in the third working area is a third current, the first current is equal to the third current, the change trend of the second current is opposite to that of the corresponding input voltage, and the second current reaches the lowest point at the peak value of the input voltage;
The control circuit comprises a first operational amplifier, wherein a first input end of the first operational amplifier receives a first voltage sampling signal, and a second input end of the first operational amplifier receives an instantaneous current reference signal;
The control circuit also comprises a reference signal generating circuit which is used for generating the instantaneous current reference signal, the reference signal generating circuit comprises a first capacitor, a charging current source and a discharging current source, the charging current source and the discharging current source are both connected with the first capacitor, the voltage on the first capacitor is regulated by controlling the charging current source and the discharging current source to charge and discharge the first capacitor, and the voltage on the first capacitor is used as the instantaneous current reference signal.
2. The efficient linear LED driving circuit of claim 1, wherein: and sampling the current flowing through the linear regulating tube to obtain a first voltage sampling signal representing output current, carrying out error compensation processing on the first voltage sampling signal and a variable average current reference signal to obtain an average current control signal, and regulating the duration of at least one of the first working area, the second working area and the third working area or regulating at least one current value of the first current, the second current and the third current according to the average current control signal so as to enable the average output current of the LED driving circuit to approach to the output current value represented by the variable average current reference signal.
3. The efficient linear LED driving circuit of claim 2, wherein: the variable average current reference signal is adjusted according to the dimming signal to adjust the average output current through the load.
4. A high efficiency linear LED driving circuit according to claim 3, wherein: the dimming signal is a PWM dimming signal or an analog dimming signal, when the dimming signal is a PWM dimming signal, the PWM dimming signal is converted into an analog voltage, and the variable average current reference signal is adjusted according to the analog voltage; when the dimming signal is an analog dimming signal, the variable average current reference signal is adjusted according to the analog dimming signal.
5. The efficient linear LED driving circuit of claim 1, wherein: the reference signal generating circuit further comprises a first comparator, a first input end of the first comparator is connected with the first capacitor, a second input end of the first comparator receives a first reference voltage, the first reference voltage represents expected values of the first current and the second current, and an output signal of the first comparator is used for controlling the charging current source to stop charging when the first capacitor voltage reaches the first reference voltage.
6. The efficient linear LED driving circuit of claim 5, wherein: in the second working area, the first phase and the second phase are included, in the first phase, the discharging current source starts to discharge the first capacitor, at the moment, the charging current source does not charge the first capacitor, at the peak time of the input voltage, the second current reaches the lowest point, the first phase ends, in the second phase, the discharging current source stops discharging, the charging current source starts to charge the first capacitor, and when the voltage of the first capacitor reaches the first reference voltage, the charging current source stops charging, and the second phase ends.
7. The efficient linear LED driving circuit of claim 5, wherein: the reference signal generating circuit also comprises a peak value detecting circuit, wherein the peak value detecting circuit is connected with a high potential end of the input voltage and is used for detecting the peak value moment of the input voltage.
8. The efficient linear LED driving circuit of claim 7, wherein: the peak detection circuit detects a peak timing of the input voltage by detecting a rate of change of the input voltage.
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| CN201811635050.1A CN109587891B (en) | 2018-12-29 | 2018-12-29 | High-efficiency linear LED driving circuit |
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| CN201811635050.1A CN109587891B (en) | 2018-12-29 | 2018-12-29 | High-efficiency linear LED driving circuit |
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| CN110798939A (en) * | 2019-11-11 | 2020-02-14 | 杰华特微电子（张家港）有限公司 | LED driving circuit and method |
| CN115665926B (en) * | 2022-11-14 | 2023-03-10 | 灿芯半导体(成都)有限公司 | LED driving chip of second-order charge-discharge circuit |
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| CN107529241A (en) * | 2016-06-22 | 2017-12-29 | 华润矽威科技（上海）有限公司 | A kind of linear Constant-power LED drive circuit of single hop and method |
| CN209806133U (en) * | 2018-12-29 | 2019-12-17 | 杰华特微电子（杭州）有限公司 | High-efficiency linear LED driving circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2010272678A (en) * | 2009-05-21 | 2010-12-02 | Sharp Corp | Led illumination circuit |
| CN104883798B (en) * | 2015-06-11 | 2017-06-16 | 矽力杰半导体技术(杭州)有限公司 | LED linear constant-current drive circuit |
| CN105979630B (en) * | 2016-06-08 | 2018-02-09 | 杰华特微电子（杭州）有限公司 | Led drive circuit |
| CN107801268B (en) * | 2016-08-31 | 2019-11-15 | 华润矽威科技（上海）有限公司 | Linear high-efficiency constant current is without stroboscopic LED driving circuit and driving method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107529241A (en) * | 2016-06-22 | 2017-12-29 | 华润矽威科技（上海）有限公司 | A kind of linear Constant-power LED drive circuit of single hop and method |
| CN209806133U (en) * | 2018-12-29 | 2019-12-17 | 杰华特微电子（杭州）有限公司 | High-efficiency linear LED driving circuit |
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