CN209806133U - High-efficiency linear LED driving circuit - Google Patents
High-efficiency linear LED driving circuit Download PDFInfo
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- CN209806133U CN209806133U CN201822246778.7U CN201822246778U CN209806133U CN 209806133 U CN209806133 U CN 209806133U CN 201822246778 U CN201822246778 U CN 201822246778U CN 209806133 U CN209806133 U CN 209806133U
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Abstract
The utility model discloses a high-efficiency linear LED drive circuit, which comprises a linear adjusting tube and a control circuit, wherein an alternating current input power supply obtains input voltage after being rectified by a rectifying circuit, the linear adjusting 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 adjusting tube, the control circuit controls the current flowing through the linear adjusting 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 adjusting tube in the first working area is first current, the current flowing through the linear adjusting tube in the second working area is second current, the current flowing through the linear adjusting tube in the third working area is third current, the first current is equal to the third current, the variation trend of the second current is opposite to the corresponding input voltage, and the second current bottoms out at a peak of the input voltage.
Description
Technical Field
The utility model relates to a power electronic technology field, concretely relates to high-efficient linear LED drive 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 carries out error processing by sampling the current flowing through the linear adjusting tube and the corresponding average current reference value so as to control the state of the linear adjusting tube, thereby realizing the output of constant current.
Fig. 1 shows waveforms of the voltage VIN, the voltage VLED at two ends of the LED, and the output current, where the voltage VIN is sinusoidal, and the voltage difference between the voltage VIN and the voltage VLED at two ends of the LED load is larger as the voltage VIN is closer to the peak position of the waveform of the voltage VIN in the power frequency period. The power consumption of the linear regulator M01 is (VIN-VLED) × Iout, i.e. when the voltage VIN is larger than the voltage VLED across the LED, the larger the power consumption of the linear regulator M01 is, the lower the system efficiency is.
In the prior art, the linear LED driving circuit has low efficiency, so 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 solutions to improve the efficiency of linear LED drive circuits to accommodate dimming applications are being sought.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims at providing a reduce linear control pipe consumption and realize the high-efficient linear LED drive circuit who adjusts luminance for it is big to solve the consumption on the linear control pipe that prior art exists, is difficult to be applied to the technical problem who adjusts luminance and use.
The technical solution of the present invention is to provide a high-efficiency linear LED driving circuit with the following structure, which comprises a linear adjusting tube and a control circuit, wherein an ac input power source obtains an input voltage after being rectified by a rectifying circuit, the linear adjusting tube is connected in series with an LED load, the input voltage supplies power to the LED load, and the control circuit is connected with a control end of the linear adjusting tube;
The control circuit controls the current flowing through the linear adjusting 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 adjusting tube in the first working area is a first current, the current flowing through the linear adjusting tube in the second working area is a second current, the current flowing through the linear adjusting 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 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 adjusting tube is sampled to obtain a first voltage sampling signal representing the output current, the first voltage sampling signal and the variable average current reference signal are subjected to error compensation processing 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 is adjusted or at least one current value of the first current, the second current and the third current is adjusted according to the average current control signal, so that the average output current of the LED driving circuit approaches to the output current value represented by the variable average current reference signal.
Optionally, the variable average current reference signal is adjusted according to the dimming signal to adjust an average output current flowing through the load.
Optionally, the dimming signal is a PWM dimming signal or an analog dimming signal, and when the dimming signal is the 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; and when the dimming signal is an analog dimming signal, adjusting the variable average current reference signal 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 the 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, the charging current source and the discharging current source are both connected to the first capacitor, and the voltage on the first capacitor is adjusted by controlling the charging and discharging of the charging current source and the discharging current source to 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 terminal of the first comparator is connected to the first capacitor, a second input terminal of the first comparator receives a first reference voltage, the first reference signal represents expected values of the first current and the second current, and an output signal of the first comparator is used to control the charging current source to stop charging when the voltage of the first capacitor reaches the first reference voltage.
Optionally, in the second operating area, the second operating area includes a first stage and a second stage, in the first stage, the discharging current source starts to discharge the first capacitor, at this time, the charging current source does not charge the first capacitor, at a peak time of the input voltage, the second current reaches a lowest point, the first stage is ended, in the second stage, the discharging current source stops discharging, the charging current source starts to charge the first capacitor, when the first capacitor voltage reaches the first reference voltage, the charging current source stops charging, and the second stage is ended.
Optionally, the reference signal generating circuit further includes a peak detection circuit, and the peak detection circuit is connected to the high potential end of the input voltage and is configured to detect 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.
Adopt the utility model discloses, compare with prior art, have following advantage: the utility model discloses set up three workspace, the first electric current of first workspace equals with the third electric current of third workspace, and the electric current of second workspace is opposite trend of change with input voltage to can realize average current's regulation, adjust variable average current reference signal through PWM signal or analog dimming signal, in order to realize adjusting luminance. The utility model discloses reduce the consumption of linear control pipe, improved system efficiency to the realization is based on PWM under the high-efficient linear LED drive circuit adjusts luminance and the simulation is adjusted luminance.
drawings
FIG. 1 is a waveform diagram illustrating operation of a prior art LED driver circuit;
Fig. 2 is a schematic block diagram of the high-efficiency linear LED of the present invention;
FIG. 3 is a waveform diagram illustrating the operation of the 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 diagram illustrating a relationship between a dimming signal and a 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 only these embodiments. The present invention covers any alternatives, modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are simplified and in non-precise proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.
The utility model discloses a basic implementation scheme as follows: the utility model discloses a LED drive circuit, including linear regulation pipe and control circuit, the alternating current input power obtains input voltage after rectifier circuit rectification, linear regulation pipe and LED load are established ties, input voltage to the power supply of LED load, control circuit with the control end of linear regulation pipe is connected;
the control circuit controls the current flowing through the linear adjusting 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 adjusting tube in the first working area is a first current, the current flowing through the linear adjusting tube in the second working area is a second current, the current flowing through the linear adjusting 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 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 a specific embodiment.
Referring to fig. 2, a schematic 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 the ac input power through the 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 sampled resistor voltage VS (i.e. the first voltage sample signal) is equal to the instantaneous current reference signal VREF, i.e. the current flowing through the LED load and the linear regulator M01 follows said instantaneous current reference signal VREF. The control circuit includes a first operational amplifier U12, a first input of the first operational amplifier U12 receiving the first voltage sampling signal VS, a second input of the first operational amplifier U12 receiving an instantaneous current reference signal VREF.
The utility model discloses a high-efficient linear LED drive circuit can also control and adjust the average current of flowing through the LED load. Sampling current flowing through a linear regulating tube to obtain a first voltage sampling signal VS representing 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 a first working area, a second working area and a 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 VC 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 VAVE. The error compensation process is realized by an error compensation circuit which comprises a second operational amplifier U11 and a compensation capacitor C2, wherein the compensation capacitor C2 is connected to the output end of the second operational amplifier U11. Two input terminals of the second operational amplifier U11 respectively receive the first voltage sampling signal VS and the variable average current reference signal VAVE. The specific implementation of adjusting the duration of at least one of the first working area, the second working area, and the third working area may be: the moment when the first operating region ends is controlled and adjusted according to the average current control signal VC to start discharging and enter the second operating region, but is not limited in this way. The specific implementation of adjusting at least one 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 not limited thereto.
Referring to fig. 3, the operating waveforms of the high efficiency linear LED driving circuit are illustrated. In the figure, T represents the entire 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, reaches the lowest value at the peak position of the input voltage, 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 both connected with the first capacitor C1, the voltage on the first capacitor C1 is adjusted 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 serves 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 the 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 charging current source I1 and the discharging current source I2, whether the charging current source I1 and the discharging current source I2 are connected or not can be controlled by a switch, whether the charging current source I1 and the discharging current source I2 are enabled or not can be controlled by a control signal, and the sizes of the charging current source I1 and the discharging current source I35. In fig. 4, switches K1 and K2 are used to control whether charging current source I1 and discharging current source I2 are connected, respectively, the input end of first comparator U13 is connected to switch K1, peak time signal tp is connected to switch K2, and switch K1 and switch K2 are controlled by other signals.
in the second working area, a first phase and a second phase are included, in the first phase, the discharging current source starts to discharge the first capacitor C1, while the charging current source I1 does not charge the first capacitor C1, the second current reaches the lowest point at the peak time of the input voltage VIN, 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, 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 sampling can be realized by a voltage dividing circuit shown in the figure, the voltage dividing circuit comprises resistors R02 and R03, the resistors R02 and R03 are connected in series, and the voltage at the common end of the resistors R02 and R03 is representative of the input voltage VIN. The common terminal of the resistors R02 and R03 is connected to a differentiating circuit, the differentiating circuit is configured to detect a 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, a voltage at the common terminal of the two capacitors represents the change rate of the input voltage VIN, and is compared with a reference signal VREF2, generally, the voltage change rate at the peak of the input voltage VIN is zero, and the reference signal VREF2 may be set to a value close to zero, and of course, the actual conditions of the application scheme, such as the setting of a reference ground, 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, and tp is used as a peak detection signal, and the signal is used for controlling the switch K2 to be switched off to stop discharging.
Referring to fig. 6, a relationship between a dimming signal and a variable average current reference signal is illustrated. The variable average current reference signal is adjusted according to the dimming signal to adjust an average output current flowing through the load. The dimming signal is a PWM dimming signal or an analog dimming signal, when the dimming signal is the 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; and when the dimming signal is an analog dimming signal, adjusting the variable average current reference signal according to the analog dimming signal. Fig. 6 illustrates an example of the PWM dimming signal, the analog voltage may be directly used as the variable average current reference signal, and the variable average current reference signal is adjusted according to the analog voltage, which may be regarded as a scaling factor of 1, or may be obtained by scaling.
Although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.
The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (10)
1. the utility model provides a high-efficient linear LED drive circuit, includes linear regulation pipe and control circuit, obtains input voltage after the alternating current input power source rectifies through rectifier circuit, linear regulation pipe and LED load are established ties, input voltage to the power supply of LED load, control circuit with the control end of linear regulation pipe is connected its characterized in that:
The control circuit controls the current flowing through the linear adjusting 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 adjusting tube in the first working area is a first current, the current flowing through the linear adjusting tube in the second working area is a second current, the current flowing through the linear adjusting 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 the corresponding input voltage, and the second current reaches the lowest point at the peak value of the input voltage.
2. A high efficiency linear LED driver circuit as claimed in claim 1, wherein: sampling current flowing through a 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 working area of a first working area, a second working area and a 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 the output current value represented by the variable average current reference signal.
3. A high efficiency linear LED driver circuit as claimed in claim 2, wherein: the variable average current reference signal is adjusted according to the dimming signal to adjust an average output current flowing through the load.
4. A high efficiency linear LED driver circuit as claimed in claim 3, wherein: the dimming signal is a PWM dimming signal or an analog dimming signal, when the dimming signal is the 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; and when the dimming signal is an analog dimming signal, adjusting the variable average current reference signal according to the analog dimming signal.
5. A high efficiency linear LED drive circuit as claimed in any one of claims 2 to 4 wherein: the control circuit comprises a first operational amplifier, wherein a first input end of the first operational amplifier receives the first voltage sampling signal, and a second input end of the first operational amplifier receives the instantaneous current reference signal.
6. a high efficiency linear LED drive circuit as claimed in claim 5, wherein: the control circuit further comprises a reference signal generating circuit 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 connected with the first capacitor, the voltage on the first capacitor is adjusted by controlling the charging and discharging of the charging current source and the discharging current source on the first capacitor, and the voltage on the first capacitor is used as the instantaneous current reference signal.
7. A high efficiency linear LED drive circuit as claimed in claim 6, 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 signal 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 voltage of the first capacitor reaches the first reference voltage.
8. A high efficiency linear LED driver circuit as claimed in claim 7, 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, the charging current source does not charge the first capacitor, the second current reaches the lowest point at the peak moment of the input voltage, the first phase is ended, in the second phase, the discharging current source stops discharging, the charging current source starts to charge the first capacitor, when the first capacitor voltage reaches the first reference voltage, the charging current source stops charging, and the second phase is ended.
9. A high efficiency linear LED driver circuit as claimed in claim 8, wherein: the reference signal generating circuit further comprises a peak detection circuit, wherein the peak detection circuit is connected with a high potential end of the input voltage and is used for detecting the peak moment of the input voltage.
10. A high efficiency linear LED driver circuit as claimed in claim 9, 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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| CN201822246778.7U CN209806133U (en) | 2018-12-29 | 2018-12-29 | High-efficiency linear LED driving circuit |
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| CN201822246778.7U CN209806133U (en) | 2018-12-29 | 2018-12-29 | High-efficiency linear LED driving circuit |
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| CN209806133U true CN209806133U (en) | 2019-12-17 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109587891A (en) * | 2018-12-29 | 2019-04-05 | 杰华特微电子（杭州）有限公司 | Efficient linear LED drive circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109587891A (en) * | 2018-12-29 | 2019-04-05 | 杰华特微电子（杭州）有限公司 | Efficient linear LED drive circuit |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Patentee after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Patentee before: JOULWATT TECHNOLOGY (HANGZHOU) Co.,Ltd. |
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