CN111315077A - LED drive circuit and LED lamp - Google Patents
LED drive circuit and LED lamp Download PDFInfo
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- CN111315077A CN111315077A CN202010286471.9A CN202010286471A CN111315077A CN 111315077 A CN111315077 A CN 111315077A CN 202010286471 A CN202010286471 A CN 202010286471A CN 111315077 A CN111315077 A CN 111315077A
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Abstract
The invention discloses an LED drive circuit and an LED lamp. The rectification circuit carries out forward rectification on the input commercial power to obtain a rectified positive waveform; when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the control circuit controls the booster circuit to boost the rectified positive waveform to the voltage value enabling the LED lamp string to be conducted so as to drive the lamp string to work in a boosting mode; when the voltage is not less than the conduction voltage, the control circuit controls the boosting circuit to stop boosting operation and the constant current device to be switched on so as to drive the lamp string to work in a linear mode. Therefore, when the absolute value of the mains supply voltage is smaller than the conduction voltage, the electric energy at the input end can be supplied to the LED lamp string for use through the booster circuit, and therefore the system efficiency is improved; when the voltage is not less than the conduction voltage, the LED lamp string is still driven to work in a linear mode, so that the system has low voltage requirement on the LED lamp string, and the design cost is facilitated.
Description
Technical Field
The invention relates to the field of LED dimming, in particular to an LED driving circuit and an LED lamp.
Background
Currently, LED (Light-Emitting Diode) lighting has become a main indoor lighting method. In many application scenarios, the brightness of the LED lamp needs to be adjusted. In the prior art, the dimming mode of the LED lamp is various, including a WIFI dimming mode, a bluetooth dimming mode, a thyristor chopping dimming mode, and the like, wherein the thyristor chopping dimming mode is the most convenient.
Referring to fig. 1, fig. 1 is a schematic diagram of a silicon controlled dimming of an LED lamp in the prior art. In fig. 1, commercial power is provided between a live line L and a zero line N, and the commercial power is supplied to an LED light string composed of a plurality of LEDs connected in series after being processed by a silicon controlled dimmer chopper, a rectifier circuit rectifier and a converter in sequence. It should be noted that, in the whole waveform remaining after chopping the mains supply, the current flowing through the thyristor dimmer is always greater than the holding current thereof to maintain the normal operation thereof, otherwise, the thyristor dimmer is not started. The LED light string only passes through the input voltage when the input voltage is greater than the on-state voltage, so that in the whole waveform remaining after the mains supply is chopped, if the LED is not on, an additional current for maintaining the operation of the silicon controlled dimmer needs to be provided.
In order to realize the normal operation of the triac dimmer, a linear triac dimming drive as shown in fig. 2 is usually adopted at present, that is, the converter in fig. 1 specifically comprises a constant current source a and a constant current source B, when the absolute value of the voltage of the mains supply is smaller than the LED on-voltage, the constant current source a is turned on, and the constant current source B is turned off; when the absolute value of the voltage of the mains supply is not less than the LED on-voltage, the constant current source B is turned on, and the constant current source a is turned off, so that the LED current is as shown in fig. 3 when the mains supply full wave occurs. It can be seen that only the current of the constant current source B is used through the LED, and the current of the constant current source a does not flow through the LED, and the converted heat is wasted, resulting in low system efficiency.
Therefore, how to provide a solution to the above technical problem is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide an LED drive circuit and an LED lamp, when the absolute value of the voltage of a mains supply is smaller than the conduction voltage of an LED lamp string, the electric energy of an input end can be supplied to the LED lamp string for use through a booster circuit, so that the system efficiency is improved; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the LED lamp string is still driven to work in a linear mode, so that the system is ensured to have lower voltage requirement on the LED lamp string, and the design cost of the LED lamp string is facilitated.
In order to solve the above technical problem, the present invention provides an LED driving circuit, including:
the rectification circuit is used for carrying out forward rectification on the commercial power subjected to chopping processing by the silicon controlled dimmer to obtain a rectified positive waveform;
the input end of the booster circuit is connected with the output end of the rectifying circuit, and the output end of the booster circuit is connected with the LED lamp string;
the constant current device is connected in a current loop between the rectifying circuit and the LED lamp string in series, and the working state of the constant current device does not influence the boosting operation of the boosting circuit;
the control circuit is respectively connected with the booster circuit and the constant current device and is used for controlling the booster circuit to boost the rectified positive waveform to a voltage value for conducting the LED lamp string when the absolute value of the voltage of commercial power is smaller than the conducting voltage of the LED lamp string so as to drive the LED lamp string to work in a boosting mode; and when the absolute value of the voltage is not less than the conduction voltage, the booster circuit is controlled to stop boosting operation, and the constant current device is controlled to be switched on, so that the LED lamp string is driven to work in a linear mode.
Preferably, the boost circuit comprises an inductor, a switching tube, a diode and an electrolytic capacitor; wherein:
the first end of the inductor is connected with the positive output end of the rectifying circuit, the second end of the inductor is respectively connected with the first end of the switch tube and the anode of the diode, the second end of the switch tube is connected with the negative output end of the rectifying circuit, the control end of the switch tube is connected with the control circuit, the cathode of the diode is respectively connected with the anode of the electrolytic capacitor and the positive input end of the LED lamp string, and the cathode of the electrolytic capacitor is connected with the negative input end of the LED lamp string;
the control circuit is specifically used for controlling the boosting operation of the boosting circuit by controlling the conduction condition of the switching tube.
Preferably, the constant current device is a constant current source; wherein:
the input end of the constant current source is connected with the negative electrode of the electrolytic capacitor and the input negative end of the LED lamp string respectively, and the output end of the constant current source is connected with the second end of the switch tube and the output negative end of the rectifying circuit respectively.
Preferably, the rectifier circuit is a full-bridge rectifier circuit.
Preferably, the control circuit includes:
the comparator is used for outputting a low level when the voltage absolute value is smaller than the breakover voltage; when the absolute value of the voltage is not less than the breakover voltage, outputting a high level;
the controller is connected with the output end of the comparator and used for controlling the boost circuit to boost the rectified positive waveform to a voltage value enabling the LED lamp string to be conducted when the low level is received, so that the LED lamp string is driven to work in a boost mode; and when the high level is received, the booster circuit is controlled to stop boosting operation, and the constant current device is controlled to be switched on so as to drive the LED lamp string to work in a linear mode.
Preferably, the comparator is integrated in the controller.
In order to solve the technical problem, the invention also provides an LED lamp, which comprises an LED lamp string and any one of the LED driving circuits.
The invention provides an LED drive circuit which comprises a rectifying circuit, a booster circuit, a constant current device and a control circuit. The rectification circuit carries out forward rectification on the commercial power subjected to chopping processing by the silicon controlled dimmer to obtain a rectified positive waveform; when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the control circuit controls the booster circuit to boost the rectified positive waveform to the voltage value enabling the LED lamp string to be conducted so as to drive the LED lamp string to work in a boosting mode; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the control circuit controls the boosting circuit to stop boosting operation and the constant current device to be turned on so as to drive the LED lamp string to work in a linear mode. Therefore, when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the electric energy at the input end can be supplied to the LED lamp string for use through the booster circuit, so that the system efficiency is improved; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the LED lamp string is still driven to work in a linear mode, so that the system is ensured to have lower voltage requirement on the LED lamp string, and the design cost of the LED lamp string is facilitated.
The invention also provides an LED lamp which has the same beneficial effect as the LED driving circuit.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic diagram of a thyristor dimming of an LED lamp in the prior art;
fig. 2 is a schematic diagram of a linear thyristor dimming driving scheme in the prior art;
FIG. 3 is a waveform diagram of LED current driven by linear thyristor dimming in the prior art;
fig. 4 is a schematic diagram of a dual-mode thyristor dimming driving scheme according to an embodiment of the present invention;
fig. 5 is a diagram of a voltage waveform of a commercial power provided by an embodiment of the present invention;
fig. 6 is a chopped waveform diagram of an output of a thyristor dimmer according to an embodiment of the present invention;
FIG. 7 is a rectified positive waveform diagram of an output of a rectifier circuit according to an embodiment of the present invention;
fig. 8 is a specific schematic diagram of a dual-mode thyristor dimming driver according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a boost scr dimming driving scheme according to an embodiment of the present invention;
fig. 10 is a waveform diagram of LED current driven by boost scr dimming according to an embodiment of the present invention;
fig. 11 is a waveform diagram of LED current driven by dual-mode thyristor dimming according to an embodiment of the present invention.
Detailed Description
The core of the invention is to provide an LED drive circuit and an LED lamp, when the absolute value of the voltage of the commercial power is smaller than the conduction voltage of the LED lamp string, the electric energy of the input end can be supplied to the LED lamp string for use through a booster circuit, thereby improving the system efficiency; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the LED lamp string is still driven to work in a linear mode, so that the system is ensured to have lower voltage requirement on the LED lamp string, and the design cost of the LED lamp string is facilitated.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 4, fig. 4 is a schematic diagram of a dual-mode thyristor dimming driving scheme according to an embodiment of the present invention.
Under the drive of dual mode silicon controlled rectifier dimming, LED drive circuit includes:
the rectification circuit 1 is used for carrying out forward rectification on commercial power subjected to chopping processing by the silicon controlled dimmer to obtain a rectified positive waveform;
the input end of the booster circuit 2 is connected with the output end of the rectifying circuit 1, and the output end of the booster circuit is connected with the LED lamp string;
the constant current device 3 is connected in a current loop between the rectifying circuit 1 and the LED lamp string in series, and the working state of the constant current device does not influence the boosting operation of the boosting circuit 2;
the control circuit 4 is respectively connected with the booster circuit 2 and the constant current device 3 and is used for controlling the booster circuit 2 to boost the rectified positive waveform to a voltage value for conducting the LED lamp string when the voltage absolute value of the commercial power is less than the conducting voltage of the LED lamp string so as to drive the LED lamp string to work in a boosting mode; and when the absolute value of the voltage is not less than the conduction voltage, the boosting circuit 2 is controlled to stop boosting operation, and the constant current device 3 is controlled to be switched on so as to drive the LED lamp string to work in a linear mode.
Specifically, the LED driving circuit of the present application includes a rectifying circuit 1, a boost circuit 2, a constant current device 3, and a control circuit 4, and its operating principle is:
referring to fig. 4 (double-oblique line represents longer cable connection), the mains supply is chopped by the silicon controlled dimmer, the silicon controlled dimmer is provided with a dimming knob, and the chopping degree of the silicon controlled dimmer to the mains supply is adjusted by adjusting the dimming knob. For example, referring to fig. 5, fig. 5 is a voltage waveform diagram of a commercial power according to an embodiment of the present invention, and the thyristor dimmer can perform about 1/2 chopping processing on the commercial power shown in fig. 5 to obtain a chopped waveform shown in fig. 6.
The chopped wave waveform obtained after the chopping processing of the silicon controlled dimmer is input into the rectifying circuit 1, and the rectifying circuit 1 carries out positive rectification on the chopped wave waveform, namely, the negative chopped wave waveform in the chopped wave waveform is converted into the positive chopped wave waveform to obtain the rectified positive waveform. For example, the chopped waveform shown in FIG. 6 may be forward rectified to produce a rectified positive waveform as shown in FIG. 7.
A rectified positive waveform obtained by forward rectification of the rectifier circuit 1 is inputted to the booster circuit 2, and the boosting operation of the booster circuit 2 is controlled by the control circuit 4. When the control circuit 4 controls the boosting circuit 2 to perform boosting operation, the boosting circuit 2 boosts the rectified positive waveform and supplies the boosted rectified positive waveform to the LED lamp string (comprising a plurality of LEDs connected in series); when the control circuit 4 controls the boosting circuit 2 to stop the boosting operation, the rectified positive waveform is directly supplied to the LED string without boosting.
It can be understood that, assuming that the commercial power enters the rectifying circuit 1 in full wave and the rectified positive waveform output by the rectifying circuit 1 is directly supplied to the LED lamp string, when the absolute value of the voltage of the commercial power is smaller than the on-state voltage of the LED lamp string, the LED lamp string is in the off-state and no current passes through; when the voltage absolute value of the commercial power is not less than the conduction voltage of the LED lamp string, the LED lamp string is in a conduction state, and current passes through the LED lamp string. Therefore, when the absolute value of the voltage of the commercial power is smaller than the conduction voltage of the LED lamp string, the rectifying positive waveform needs to be boosted to the voltage value for conducting the LED lamp string by the aid of the boosting circuit 2 so as to drive the LED lamp string to work, and therefore electric energy of an input end is not wasted. When the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the rectified positive waveform is directly supplied to the LED lamp string through the constant current device 3 without the aid of the boosting operation of the boosting circuit 2.
Based on this, when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the control circuit 4 controls the constant current device 3 to be turned off, and controls the boosting circuit 2 to boost the rectified positive waveform to the voltage value enabling the LED lamp string to be conducted, so as to drive the LED lamp string to work in the boosting mode. When the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the control circuit 4 controls the boosting circuit 2 to stop boosting operation and controls the constant current device 3 to be switched on so as to drive the LED lamp string to work in a linear mode.
The invention provides an LED drive circuit which comprises a rectifying circuit, a booster circuit, a constant current device and a control circuit. The rectification circuit carries out forward rectification on the commercial power subjected to chopping processing by the silicon controlled dimmer to obtain a rectified positive waveform; when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the control circuit controls the booster circuit to boost the rectified positive waveform to the voltage value enabling the LED lamp string to be conducted so as to drive the LED lamp string to work in a boosting mode; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the control circuit controls the boosting circuit to stop boosting operation and the constant current device to be turned on so as to drive the LED lamp string to work in a linear mode.
Therefore, when the voltage absolute value of the commercial power is smaller than the conduction voltage of the LED lamp string, the electric energy at the input end can be supplied to the LED lamp string for use through the booster circuit, so that the system efficiency is improved; when the absolute value of the voltage of the commercial power is not less than the conduction voltage of the LED lamp string, the LED lamp string is still driven to work in a linear mode, so that the system is ensured to have lower voltage requirement on the LED lamp string, and the design cost of the LED lamp string is facilitated.
On the basis of the above-described embodiment:
referring to fig. 8, fig. 8 is a specific schematic diagram of a dual-mode thyristor dimming driving according to an embodiment of the present invention.
As an alternative embodiment, the boost circuit 2 includes an inductor L1, a switching tube Q, a diode D, and an electrolytic capacitor C; wherein:
the first end of the inductor L1 is connected with the positive output end of the rectifying circuit 1, the second end of the inductor L1 is connected with the first end of the switch tube Q and the anode of the diode D respectively, the second end of the switch tube Q is connected with the negative output end of the rectifying circuit 1, the control end of the switch tube Q is connected with the control circuit 4, the cathode of the diode D is connected with the anode of the electrolytic capacitor C and the positive input end of the LED lamp string respectively, and the cathode of the electrolytic capacitor C is connected with the negative input end of the LED lamp string;
the control circuit 4 is specifically configured to control the boosting operation of the boosting circuit 2 by controlling the conduction condition of the switching tube Q.
Specifically, the boost circuit 2 of the present application includes an inductor L1, a switching tube Q, a diode D, and an electrolytic capacitor C, and its operating principle is:
during the boosting operation of the boosting circuit 2, when the control circuit 4 controls the switching tube Q to be conducted (the switching tube Q is equivalent to a conducting wire), the diode D prevents the electrolytic capacitor C from discharging to the ground, the output voltage of the rectifying circuit 1 flows through the inductor L1, the current in the inductor L1 increases at a certain rate (the rate is related to the magnitude of the inductor value), and as the inductor current increases, some energy is stored in the inductor L1; when the control circuit 4 controls the switch Q to be turned off, the current flowing through the inductor L1 does not immediately become 0 due to the current holding characteristic of the inductor L1, but slowly changes to 0 by charging the electrolytic capacitor C, and the voltage across the electrolytic capacitor C rises, and at this time, the voltage across the electrolytic capacitor C is already higher than the output voltage of the rectifier circuit 1. The switching on and off process of the switching tube Q is repeated continuously, and voltage continuously higher than the output voltage of the rectifying circuit can be obtained at two ends of the electrolytic capacitor C, so that the boosting operation is realized. When the boosting circuit 2 stops the boosting operation, the control circuit 4 controls the switching tube Q to be turned off.
As an alternative embodiment, the constant current device 3 is specifically a constant current source S; wherein:
the input end of the constant current source S is respectively connected with the cathode of the electrolytic capacitor C and the input negative end of the LED lamp string, and the output end of the constant current source S is respectively connected with the second end of the switch tube Q and the output negative end of the rectifying circuit 1.
Specifically, the constant current device 3 of the present application is specifically a constant current source S, and the working principle thereof is as follows: when the boosting circuit 2 stops boosting operation, the constant current source S is switched on, the output voltage V _ Bridge of the rectifying circuit 1 returns to V _ GND through the inductor L1, the diode D, LED light string and the constant current source S, and the system works in a linear mode.
It should be noted that, the boost mode and the linear mode are selected for the dual-mode driving in the present application because:
1) the boost mode is not considered, only the linear mode is considered, the LED driving circuit is analyzed, that is, the driving circuit shown in fig. 2 is used for driving the whole waveform period, and the system efficiency is low (the background art has been described in detail, and is not described herein again).
2) The LED driving circuit was analyzed, considering only the boost mode, regardless of the linear mode: referring to fig. 9, fig. 9 is a schematic diagram of a boost-type thyristor dimming driving scheme according to an embodiment of the present invention. If the whole waveform period is controlled by the boost mode, the waveform of the LED current when the commercial power is full wave is as shown in fig. 10. However, as can be seen from analyzing the circuit architecture shown in fig. 9, the circuit architecture requires that the voltage of the LED light string is higher than the peak value of the mains voltage, otherwise, the voltage of the LED light string is not controllable, that is, when the LED light string is designed under the circuit architecture, the voltage of the LED light string is higher than the peak value of the mains voltage, for example, the mains effective value is 220V, the mains peak value is 312V, and the voltage of the LED light string is higher than 312V, which results in a large number of LEDs connected in series in the LED light string and a high cost.
3) The LED driving circuit is analyzed in consideration of both the boost mode and the linear mode, that is, the whole waveform period is driven by the driving circuit as shown in fig. 8: when the absolute value of the voltage of the commercial power is smaller than the conduction voltage of the LED lamp string, the control circuit 4 controls the booster circuit 2 to boost the rectified positive waveform to the voltage value which enables the LED lamp string to be conducted, so that the LED lamp string is driven to work in a boosting mode; when the absolute value of the voltage of the commercial power is not less than the on-state voltage of the LED light string, the control circuit 4 controls the voltage boosting circuit 2 to stop the voltage boosting operation and turn on the constant current source S, so as to drive the LED light string to operate in the linear mode (the LED current waveform is shown in fig. 11 when the commercial power is full wave). Therefore, the dual-mode driving architecture gives consideration to the system efficiency problem and the LED cost problem, and reduces the system cost while improving the system efficiency.
As an alternative embodiment, the rectifier circuit 1 is embodied as a full-bridge rectifier circuit.
Specifically, rectifier circuit 1 of this application specifically chooses full bridge rectifier circuit for use, and full bridge rectifier circuit includes four diodes, and these four two liang of docks of diode. When the full-bridge rectifier circuit inputs the positive half part of the sine wave, the two diodes are conducted to obtain positive output; when the negative half of the sine wave is input, the other two diodes conduct, and since the two diodes are connected in reverse, the output is also positive.
In addition, the full-bridge rectifier circuit can be externally packaged by insulating plastics, and a metal shell is added outside the insulating layer for packaging, so that heat dissipation is enhanced.
As an alternative embodiment, the control circuit 4 comprises:
the comparator is used for inputting the voltage absolute value of the mains supply connected to the positive end and the conduction voltage of the LED lamp string connected to the negative end, and outputting a low level when the voltage absolute value is smaller than the conduction voltage; when the absolute value of the voltage is not less than the breakover voltage, outputting a high level;
the controller is connected with the output end of the comparator and is used for controlling the booster circuit 2 to boost the rectified positive waveform to a voltage value enabling the LED lamp string to be conducted when receiving a low level so as to drive the LED lamp string to work in a boost mode; and when receiving the high level, controlling the boosting circuit 2 to stop boosting operation and the constant current device 3 to be switched on so as to drive the LED lamp string to work in a linear mode.
Specifically, the control circuit 4 of the present application includes a comparator and a controller, and its operating principle is:
the comparator is used for comparing the voltage absolute value of the mains supply with the conduction voltage of the LED lamp string, and particularly outputs a low level when the voltage absolute value of the mains supply is smaller than the conduction voltage of the LED lamp string; when the voltage absolute value of the commercial power is not less than the conduction voltage of the LED lamp string, the comparator outputs a high level. The comparator inputs the generated level to the controller, the controller drives the LED lamp string to work based on the dual-mode driving principle, and specifically, when the low level is received, the controller controls the booster circuit 2 to boost the rectified positive waveform to a voltage value enabling the LED lamp string to be conducted, so that the LED lamp string is driven to work in a boost mode; when receiving the high level, the controller controls the boosting circuit 2 to stop boosting operation and the constant current device 3 to be switched on so as to drive the LED lamp string to work in a linear mode.
As an alternative embodiment, the comparator is integrated in the controller.
Specifically, the comparator can be integrated into the controller, that is, the controller has a function of comparing the absolute voltage value of the commercial power with the magnitude of the on-state voltage of the LED light string.
Of course, the control circuit 4 of the present application may also only include a controller, and the controller implements a function of comparing the absolute voltage value of the utility power and the magnitude of the on-state voltage of the LED light string through software.
The application also provides an LED lamp which comprises the LED lamp string and any one of the LED driving circuits.
For the introduction of the LED lamp provided in the present application, please refer to the above-mentioned embodiment of the LED driving circuit, which is not repeated herein.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. An LED driving circuit, comprising:
the rectification circuit is used for carrying out forward rectification on the commercial power subjected to chopping processing by the silicon controlled dimmer to obtain a rectified positive waveform;
the input end of the booster circuit is connected with the output end of the rectifying circuit, and the output end of the booster circuit is connected with the LED lamp string;
the constant current device is connected in a current loop between the rectifying circuit and the LED lamp string in series, and the working state of the constant current device does not influence the boosting operation of the boosting circuit;
the control circuit is respectively connected with the booster circuit and the constant current device and is used for controlling the booster circuit to boost the rectified positive waveform to a voltage value for conducting the LED lamp string when the absolute value of the voltage of commercial power is smaller than the conducting voltage of the LED lamp string so as to drive the LED lamp string to work in a boosting mode; and when the absolute value of the voltage is not less than the conduction voltage, the booster circuit is controlled to stop boosting operation, and the constant current device is controlled to be switched on, so that the LED lamp string is driven to work in a linear mode.
2. The LED driving circuit according to claim 1, wherein the boost circuit comprises an inductor, a switching tube, a diode and an electrolytic capacitor; wherein:
the first end of the inductor is connected with the positive output end of the rectifying circuit, the second end of the inductor is respectively connected with the first end of the switch tube and the anode of the diode, the second end of the switch tube is connected with the negative output end of the rectifying circuit, the control end of the switch tube is connected with the control circuit, the cathode of the diode is respectively connected with the anode of the electrolytic capacitor and the positive input end of the LED lamp string, and the cathode of the electrolytic capacitor is connected with the negative input end of the LED lamp string;
the control circuit is specifically used for controlling the boosting operation of the boosting circuit by controlling the conduction condition of the switching tube.
3. The LED driving circuit according to claim 2, wherein the constant current means is specifically a constant current source; wherein:
the input end of the constant current source is connected with the negative electrode of the electrolytic capacitor and the input negative end of the LED lamp string respectively, and the output end of the constant current source is connected with the second end of the switch tube and the output negative end of the rectifying circuit respectively.
4. The LED driving circuit according to claim 1, wherein the rectifier circuit is in particular a full-bridge rectifier circuit.
5. The LED drive circuit of claim 1, wherein the control circuit comprises:
the comparator is used for outputting a low level when the voltage absolute value is smaller than the breakover voltage; when the absolute value of the voltage is not less than the breakover voltage, outputting a high level;
the controller is connected with the output end of the comparator and used for controlling the boost circuit to boost the rectified positive waveform to a voltage value enabling the LED lamp string to be conducted when the low level is received, so that the LED lamp string is driven to work in a boost mode; and when the high level is received, the booster circuit is controlled to stop boosting operation, and the constant current device is controlled to be switched on so as to drive the LED lamp string to work in a linear mode.
6. The LED driver circuit of claim 5, wherein the comparator is integrated in the controller.
7. An LED lamp comprising an LED string and an LED driving circuit according to any one of claims 1 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010286471.9A CN111315077A (en) | 2020-04-13 | 2020-04-13 | LED drive circuit and LED lamp |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010286471.9A CN111315077A (en) | 2020-04-13 | 2020-04-13 | LED drive circuit and LED lamp |
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| Publication Number | Publication Date |
|---|---|
| CN111315077A true CN111315077A (en) | 2020-06-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010286471.9A Pending CN111315077A (en) | 2020-04-13 | 2020-04-13 | LED drive circuit and LED lamp |
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|---|---|
| CN (1) | CN111315077A (en) |
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2020
- 2020-04-13 CN CN202010286471.9A patent/CN111315077A/en active Pending
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