CN114126149A

CN114126149A - LED drive circuit, LED constant current driver and lighting equipment

Info

Publication number: CN114126149A
Application number: CN202111402848.3A
Authority: CN
Inventors: 陈�峰
Original assignee: Opple Lighting Co Ltd
Current assignee: Opple Lighting Co Ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-03-01

Abstract

The invention discloses an LED drive circuit, an LED constant current driver and a lighting device, wherein the LED drive circuit comprises: the device comprises a rectifying module, an energy storage filter capacitor, a sampling module, a control module and a ripple wave eliminating module; the rectifying module is used for rectifying the input voltage; the sampling module is used for sampling the voltage output by the rectifying module so as to output a feedback signal to the control module; the energy storage filter capacitor and the control module are connected between the rectifying module and the ground in series and used for charging and storing energy in the input current on-time and providing driving current for the LED lamp bank in the input current off-time; the control module is electrically connected with the sampling module and used for controlling the current of the LED lamp bank according to the feedback signal and a current signal on a first sampling resistor in the control module and controlling the conduction time and the charging current of the energy storage filter capacitor; the ripple eliminating module is connected with the LED lamp bank in series and then connected with the energy storage filter capacitor in parallel, and is used for controlling the current of the LED lamp bank and eliminating the ripple current.

Description

LED drive circuit, LED constant current driver and lighting equipment

Technical Field

The invention relates to the technical field of illumination, in particular to an LED driving circuit, an LED constant-current driver and illumination equipment.

Background

With the development of lighting technology, LED lamps have been commonly used. Before the LED lamp is turned on, the LED lamp needs to be driven and turned on by a driving circuit.

Currently, a linear driving circuit is generally used to drive an LED lamp. The linear driving circuit has many advantages, such as simple circuit device structure, less component number, convenient production and debugging, convenient automatic production, wide application in the field of general illumination, etc. In the prior art, the LED lamp is switched on by the multi-section linear driving circuit in a time-sharing control mode, so that the waveform in the switching-on time of the input current basically changes along with the change of the working waveform of the input voltage, and the power factor value of the LED driving circuit is improved.

However, the time-sharing conduction of the LED lamp causes a large current ripple to occur in the whole power frequency period, and the performance requirement of no strobe output cannot be met.

Therefore, there is a need to address the problems of the prior art.

Disclosure of Invention

The invention provides an LED drive circuit, an LED constant current driver and lighting equipment, aiming at providing an improved LED drive circuit with linear width input and no stroboflash, which can eliminate ripples of LED drive current in different input voltage ranges through a ripple elimination module, and further inhibit charging current under different input voltages by sampling bus voltage to introduce a negative feedback mechanism so as to realize constant power compensation effect; and the conduction angle of the input current is enlarged by controlling the charging current and the conduction time of the energy storage filter capacitor, so that the function of power factor calibration is realized.

According to an aspect of the present invention, an embodiment of the present invention provides an LED driving circuit electrically connected to an LED lamp set, the LED driving circuit including: the device comprises a rectifying module, an energy storage filter capacitor, a sampling module, a control module and a ripple wave eliminating module, wherein the rectifying module is used for rectifying input voltage; the sampling module is used for sampling the voltage output by the rectifying module so as to output a feedback signal to the control module; the energy storage filter capacitor and the control module are connected between the rectifying module and the ground in series, and the energy storage filter capacitor is used for charging and storing energy in the input current on-time and providing driving current for the LED lamp set in the input current off-time; the control module is electrically connected with the sampling module and used for controlling the current of the LED lamp set according to a feedback signal and a current signal on a first sampling resistor in the control module and controlling the conduction time and the charging current of the energy storage filter capacitor; the ripple eliminating module is connected with the LED lamp bank in series and then connected with the energy storage filter capacitor in parallel, and the ripple eliminating module is used for controlling the current of the LED lamp bank and eliminating the ripple current.

Optionally, the sampling module is connected in series between the rectifying module and ground.

Optionally, an input end of the sampling module is connected between the LED lamp set and the ripple elimination module, and an output end of the sampling module is connected to the control module.

Optionally, the sampling module includes a first voltage dividing resistor and a second voltage dividing resistor connected in series, and the first voltage dividing resistor and the second voltage dividing resistor are used for dividing the voltage output by the rectifying module.

Optionally, the sampling module further includes a two-stage RC filter circuit for eliminating power frequency ripple noise of the rectified input voltage.

Optionally, the RC filter circuit includes a first filter resistor, a second filter resistor, a first filter capacitor, and a second filter capacitor; the first end of the first filter resistor is connected with a common node of the first divider resistor and the second divider resistor, and the second end of the first filter resistor is respectively connected with the first end of the second filter resistor and the first end of the first filter capacitor; a first end of the second filter resistor is connected with a first end of the first filter capacitor, and a second end of the second filter resistor is respectively connected with an input end of the control module and a first end of the second filter capacitor; and the second end of the first filter capacitor and the second end of the second filter capacitor are both grounded.

Optionally, the control module includes a first current source, a first operational amplifier, a first switch tube, and a third voltage dividing resistor; the input end of the first current source is connected with the input end of the control module, and the output end of the first current source is respectively connected with the inverting input end of the first operational amplifier and the first end of the third voltage dividing resistor; the positive phase input end of the first operational amplifier is used for receiving a reference voltage, and the output end of the first operational amplifier is connected with the control end of the first switching tube; a first end of the third voltage-dividing resistor is connected with an inverting input end of the first operational amplifier, and a second end of the third voltage-dividing resistor is respectively connected with a first end of the first switching tube and a first end of the first sampling resistor; the first end of the first switching tube is connected with the first end of the first sampling resistor, and the second end of the first switching tube is connected with the energy storage filter capacitor; the second end of the first sampling resistor is grounded.

Optionally, the ripple cancellation module includes a second switching tube, a second sampling resistor, and a first capacitor; the first end of the second switch tube is connected with the LED lamp group, the second end of the second switch tube is connected with the first end of the second sampling resistor, and the control end of the second switch tube is connected with the first end of the first capacitor; and the second end of the second sampling resistor is connected with the second end of the first capacitor.

Optionally, the ripple cancellation module further includes a zener diode and a first resistor; the cathode of the voltage stabilizing diode and the first end of the first resistor are both connected with the first end of the second switch tube; and the anode of the voltage stabilizing diode and the second end of the first resistor are both connected with the control end of the second switching tube.

Optionally, the rectifying module, the energy storage filter capacitor, the control module and the ground are sequentially connected in series.

Optionally, the rectifying module, the control module, the energy storage filter capacitor and the ground are sequentially connected in series.

According to another aspect of the present invention, an embodiment of the present invention provides an LED constant current driver, which includes the LED driving circuit according to any embodiment of the present invention.

According to still another aspect of the invention, an embodiment of the invention provides a lighting device, which includes the LED constant current driver and an LED lamp group electrically connected with the LED constant current driver.

The embodiment of the invention provides an LED drive circuit, an LED constant-current driver and lighting equipment, and aims to provide an improved LED drive circuit with linear width input and no stroboflash, ripples of LED drive current can be eliminated in different input voltage ranges through a ripple elimination module, and charging current under different input voltages is further inhibited by sampling bus voltage to introduce a negative feedback mechanism so as to realize a constant power compensation effect; and the conduction angle of the input current is enlarged by controlling the charging current and the conduction time of the input energy storage filter capacitor, so that the function of power factor calibration is realized.

Drawings

The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.

Fig. 1 is a functional schematic diagram of an LED driving circuit according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of an LED driving circuit according to the embodiment of the present invention.

Fig. 3 is a circuit diagram of an LED driving circuit according to another embodiment of the present invention.

Fig. 4 is a waveform diagram of an input current of a prior art LED driving circuit and the LED driving circuit.

Fig. 5 is a schematic diagram of the input current of the LED driving circuit and the waveform of the LED driving circuit according to the present invention.

Fig. 6 is a block diagram of an LED constant current driver and an illumination device according to an embodiment of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the 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.

The terms "first", "second" and "first" are used herein for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Referring to fig. 1, an embodiment of the present invention provides an LED driving circuit 1000, electrically connected to an LED lamp set 200, where the LED driving circuit 1000 includes: the rectifier module 110, the energy storage filter capacitor EC1, the sampling module 120, the control module 130, and the ripple cancellation module 140. The rectifying module 110 is used for rectifying the input voltage AC. Wherein the input voltage AC may be an input voltage of the mains. The rectifier module 110 may be a bridge rectifier module.

The sampling module 120 is configured to sample the voltage output by the rectifying module 110 to output a feedback signal to the control module.

The energy storage filter capacitor EC1 and the control module 130 are connected in series between the rectifying module 110 and the ground GND, and the energy storage filter capacitor EC1 is used for charging energy storage during the input current on-time and providing driving current for the LED lamp set 200 during the input current off-time.

The control module 130 is electrically connected to the sampling module 120, and is configured to control the current of the LED lamp set 200 according to a feedback signal and a current signal on a first sampling resistor inside the control module itself, and control the on-time and the charging current of the energy storage filter capacitor EC 1. Here, the feedback signal refers to a feedback signal obtained by sampling the rectified input voltage.

The ripple cancellation module 140 is connected in series with the LED lamp set 200 and then connected in parallel with the energy storage filter capacitor EC1, and the ripple cancellation module 140 is configured to control the current of the LED lamp set 200 and cancel the ripple current.

The LED driving circuit 1000 of the present invention is an improved LED driving circuit with linear width input and no stroboflash. The LED driving circuit 1000 can eliminate ripples of the LED driving current in different input voltage ranges through the ripple elimination module 140, and further suppress the charging current under different input voltages by sampling the bus voltage to introduce a negative feedback mechanism to achieve a constant power compensation effect; and the conduction angle of the input current is enlarged by controlling the charging current and the conduction time of the input energy storage filter capacitor EC1, so that the function of power factor calibration is realized.

The circuit connection manner of the LED driving circuit 1000 will be further described below with reference to fig. 1 and 2.

Specifically, the specific connection manner of the sampling module 120 includes, but is not limited to, the following two types:

in this embodiment, the sampling module 120 is connected in series between the rectifying module 110 and the ground GND. In other embodiments, as shown in fig. 3, the input end of the sampling module 120 is connected between the LED lamp set 200 and the ripple cancellation module 140, and the output end of the sampling module 120 is connected to the control module 130.

Further, in the present embodiment, as shown in fig. 2, the sampling module 120 includes a first voltage-dividing resistor R1 and a second voltage-dividing resistor R2 connected in series, and the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 are used for dividing the voltage output by the rectifying module 110.

Optionally, the sampling module 120 further includes a two-stage RC filter circuit for eliminating power frequency ripple noise of the rectified input voltage AC. Specifically, the RC filter circuit includes a first filter resistor R3, a second filter resistor R4, a first filter capacitor C1, and a second filter capacitor C2. A first end of the first filter resistor R3 is connected to a common node of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2, and a second end of the first filter resistor R3 is connected to a first end of the second filter resistor R4 and a first end of the first filter capacitor C1, respectively. A first terminal of the second filter resistor R4 is connected to a first terminal of the first filter capacitor C1, and a second terminal of the second filter resistor R4 is connected to the input terminal of the control module 130 and the first terminal of the second filter capacitor C2, respectively. The second terminal of the first filter capacitor C1 and the second terminal of the second filter capacitor C2 are both connected to ground GND.

Therefore, in the present embodiment, the sampling module 120 includes a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a first filter resistor R3, a second filter resistor R4, a first filter capacitor C1, and a second filter capacitor C2. The first filter resistor R3, the second filter resistor R4, the first filter capacitor C1 and the second filter capacitor C2 form a group of two-stage RC filter circuits, so that a power frequency voltage ripple signal introduced in the process of sampling a bus voltage (namely, rectified input voltage AC) signal is eliminated, and a clean and effective feedback signal of the rectified input voltage is provided for a rear-stage circuit. The feedback signal is a voltage signal (or feedback voltage) that is in a positive comparison with the rectified input voltage.

Specifically, the specific connection manner of the control module 130 includes, but is not limited to, the following two types:

in this embodiment, the rectifying module 110, the energy storage filter capacitor EC1, the control module 130 and the ground GND are sequentially connected in series. In other embodiments, the rectifying module 110, the control module 130, the energy storage filter capacitor EC1 and the ground GND are connected in series in sequence.

Further, in the present embodiment, as shown in fig. 2, the control module 130 includes a first current source IA1, a first operational amplifier U1, a first switching tube Q1, a first sampling resistor Rcs1, and a third voltage dividing resistor R5. An input terminal of the first current source IA1 is connected to an input terminal of the control module 130, and an output terminal of the first current source IA1 is connected to an inverting input terminal of the first operational amplifier U1 and a first terminal of the third voltage-dividing resistor R5, respectively. The non-inverting input terminal of the first operational amplifier U1 is configured to receive a reference voltage, and the output terminal of the first operational amplifier U1 is connected to the control terminal of the first switching transistor Q1. A first end of the third voltage dividing resistor R5 is connected to an inverting input terminal of the first operational amplifier U1, and a second end of the third voltage dividing resistor R5 is connected to a first end of the first switch Q1 and a first end of the first sampling resistor Rcs1, respectively. A first terminal of the first switch Q1 is connected to a first terminal of the first sampling resistor Rcs1, and a second terminal of the first switch Q1 is connected to the energy storage filter capacitor EC 1. The second terminal of the first sampling resistor Rcs1 is grounded to GND. The positive phase input end of the first operational amplifier U1 is configured to receive a reference voltage, the negative phase input end of the first operational amplifier U1 is configured to obtain a feedback voltage based on the current source, the third voltage dividing resistor R5 and the first sampling resistor Rcs1, the first operational amplifier U1 is configured to compare the reference voltage received by the positive phase input end with the feedback voltage obtained by the negative phase input end, and when the reference voltage received by the positive phase input end is greater than the feedback voltage obtained by the negative phase input end, the first switching tube Q1 is controlled to be turned on, and when the reference voltage received by the positive phase input end is less than the feedback voltage obtained by the negative phase input end, the first switching tube Q1 is controlled to be turned off.

Further, when the reference voltage received by the non-inverting input terminal is greater than the feedback voltage of the inverting input terminal, the first operational amplifier U1 controls the first switch Q1 to be turned on, and the energy storage filter capacitor EC1 starts to charge. In this way, the feedback voltage collected by the inverting input terminal gradually increases until the reference voltage of the non-inverting input terminal is equal to the feedback voltage of the inverting input terminal, and the first switching tube Q1 is controlled to be turned off. Therefore, the reference voltage received by the non-inverting input end is larger than the feedback voltage of the inverting input end, the first operational amplifier U1 controls the first switch tube Q1 to be switched on, the energy storage filter capacitor EC1 starts to be charged, and the cycle is dynamically switched on or off, so that the time from the start of charging to the full charge of the energy storage filter capacitor EC1 is suppressed.

With continued reference to fig. 2, in the present embodiment, the ripple cancellation module 140 includes a second switch Q2, a second sampling resistor Rcs2, and a first capacitor C3. A first end of the second switch tube Q2 is connected to the LED lamp set 200, a second end of the second switch tube Q2 is connected to a first end of a second sampling resistor Rcs2, and a control end of the second switch tube Q2 is connected to a first end of the first capacitor C3. A second terminal of the second sampling resistor Rcs2 is connected to a second terminal of the first capacitor C3.

Optionally, the ripple cancellation module 140 further includes a zener diode ZD1 and a first resistor R6; the cathode of the zener diode ZD1 and the first end of the first resistor R6 are both connected with the first end of the second switching tube Q2; an anode of the zener diode ZD1 and a second end of the first resistor R6 are both connected to the control end of the second switching tube Q2. The zener diode ZD1 and the first resistor R6 are used to provide a proper charging current at the power-on instant of the LED driving circuit 1000, so as to charge the first capacitor C3. When the charging current is larger, the voltage of the first capacitor C3 is faster to build up, and when the voltage of the first capacitor C3 is greater than the threshold voltage of the control terminal (i.e., the gate of the MOS transistor) of the second switch transistor Q2, the second switch transistor Q2 is turned on, so that the fast response turn-on of the second switch transistor Q2 can be ensured. If the zener diode ZD1 and the first resistor R6 are not provided, the turn-on speed of the second switch Q2 is affected, and even the turn-on time is long, so that the energy storage filter capacitor EC1 is easily damaged due to the fact that the voltage of the energy storage filter capacitor EC1 rises very high instantly.

Therefore, in this embodiment, the ripple cancellation module 140 detects the current of the second sampling resistor Rcs2 connected to the second terminal (i.e., the source of the MOS transistor) of the second switching transistor Q2 to control the voltage variation of the control terminal (i.e., the gate of the MOS transistor) of the second switching transistor Q2, and further adjusts the voltage of the LED lamp set 200 connected to the first terminal (i.e., the drain of the MOS transistor) of the second switching transistor Q2, so as to achieve the purposes of current control of the LED lamp set 200 and cancellation of the ripple current.

In addition, the energy storage filter capacitor EC1, the LED lamp set 200, and the ripple cancellation module 140 form a loop, when the energy storage filter capacitor EC1 discharges, the loop provides the driving current of the LED lamp set 200, and the ripple cancellation module 140 can still filter the power frequency ripple in the driving current input to the LED lamp set 200.

The operation of the LED driving circuit 1000 will be further described with reference to fig. 2.

When the LED driving circuit 1000 is initially powered on, the input voltage AC is an alternating voltage, and after being rectified by the rectifying module 110, the energy storage filter capacitor EC1 is charged. At this time, since the first switching tube Q1 is not yet fully turned on, the voltage across the energy storage filter capacitor EC1 rises slowly. When the voltage across the energy storage filter capacitor EC1 is much lower than the forward conduction voltage of the LED lamp set 200 (LED lamp set voltage for short), the LED lamp set 200 cannot be lit because it cannot obtain sufficient driving current; when the voltage across the energy storage filter capacitor EC1 begins to be greater than the voltage of the LED lamp set, the LED lamp set 200 gradually obtains sufficient driving current to enter a normal stable operating state.

After the LED driving circuit 1000 enters a stable operating state, during the input current conducting period, the first voltage dividing resistor R1 and the second voltage dividing resistor R2 sample the rectified bus voltage signal (i.e., the rectified input voltage AC), and the rectified bus voltage signal is processed by a two-stage RC filter circuit to eliminate the power frequency ripple voltage noise on the introduced bus voltage, wherein the RC time constant is usually greater than the time of two power frequency cycles. The sampling signal (actually, a voltage signal) generated by the current source IA1 is processed by internal logic of the circuit and then output to the inverting input terminal of the first operational amplifier U1. If the input voltage is higher, the sampling signal (i.e., the voltage signal) sampled by the sampling module 120 is larger, and the output current generated by the current source IA1 is also larger, so that the control current flowing through the first sampling resistor Rcs1 through the third voltage dividing resistor R5 is larger, and then the voltage at the inverting input terminal of the first operational amplifier U1 connected to one end of the first sampling resistor Rcs1 is also larger, and since the reference voltage Vref at the non-inverting input terminal of the first operational amplifier U1 is a constant value, the voltage at the output terminal of the first operational amplifier U1 for driving the first switch tube Q1 is smaller, so that the equivalent impedance of the first switch tube Q1 is relatively larger, that is, the current flowing through the first switch tube Q1 is relatively smaller, thereby further limiting the power increase of the LED lamp set 200 of the LED driving circuit 1000. Conversely, when the input voltage is lower, the sampling signal (voltage signal) sampled by the sampling module 120 is smaller, and similarly, the output current generated by the current source IA1 is smaller, so that the control current flowing through the first sampling resistor Rcs1 through the third voltage dividing resistor R5 is smaller, and then the voltage at the inverting input terminal of the first operational amplifier U1 connected to one end of the first sampling resistor Rcs1 is also smaller, and since the reference voltage Verf at the non-inverting input terminal of the first operational amplifier U1 is a constant value, the voltage at the output terminal of the first operational amplifier U1 for driving the first switching tube Q1 is made larger, so that the equivalent impedance of the first switching tube Q1 is relatively smaller, that is, the current flowing through the first switching tube Q1 is relatively larger, thereby further limiting the power reduction of the LED lamp set 200 of the LED driving circuit 1000. In other words, the above-mentioned operating mechanism realizes the circuit function of the wide voltage input constant power system, i.e., Pin — Vin × Iin, where the variable of Vin (input voltage) and the variable of Iin (input current) are in an inversely proportional relationship. The wide voltage input is only suitable for 200VAC to 240VAC compared with the conventional linear driving design scheme, and the LED driving circuit can meet the application of the rated input voltage range with the deviation of plus or minus 10%. In addition, the constant power here means that when the input voltage changes, the magnitude of the input current can be indirectly controlled by controlling the operating current of the LED lamp set (the operating current of the LED lamp set is in a positive correlation with the input current), so as to realize the constant power function.

Therefore, the LED driving circuit 1000 of the present invention further suppresses the charging current under different input voltages by sampling the bus voltage to introduce a negative feedback mechanism to achieve a constant power compensation effect.

It should be noted that the negative feedback described above refers to a negative feedback circuit formed by the sampling module connected to the current source and the third voltage dividing resistor R5. When the input voltage is larger, the output current generated by the current source is larger, and the current I flowing through the first sampling resistor Rcs1 is (Vref-IA 1R 5)/Rcs1, where Vref is the reference voltage of the non-inverting input terminal of the first operational amplifier U1, IA1 is the output current generated by the current source, R5 is the third voltage dividing resistor, and Rcs1 is the first sampling resistor. Based on the above formula, it can be said that, when the output current of the current source is larger, the current flowing through the first sampling resistor is smaller, and further the current flowing through the LED lamp group is smaller (the first switching tube Q1, the first sampling resistor Rcs1 and the LED lamp group are connected in series, and the currents are equal).

During the period when the input current is off, the energy storage filter capacitor EC1 works in parallel with the LED lamp set 200 and the ripple elimination module 140 connected in series, so as to provide a stable working current for the LED lamp set 200. The first switching tube Q1 in the sampling module 120 is continuously and dynamically turned on and medium, so that the time from the beginning of charging to the full charging of the energy storage filter capacitor EC1 is prolonged, that is, the conduction angle of the current after the rectified output is enlarged, and the power factor of the LED driving circuit 1000 is high.

The operation of the ripple cancellation module 140 will be further described below. When the voltage across the energy storage filter capacitor EC1 is lower than the driving voltage required by the steady-state operation of the LED lamp set 200, the current flowing through the second switch tube Q2 and the second sampling resistor Rcs2 decreases, that is, the voltage across the second terminal of the second switch tube Q2 (i.e., the source of the MOS transistor) decreases, so that the voltage across the first capacitor C3 connected to the control terminal of the second switch tube Q2 (i.e., the gate of the MOS transistor) increases, that is, the on-state voltage of the control terminal of the second switch tube Q2 (i.e., the gate of the MOS transistor) increases, so that the equivalent impedance of the second switch tube Q2 relatively decreases, and the voltage across the first terminal of the second switch tube Q2 (i.e., the drain of the MOS transistor) decreases accordingly. Conversely, when the voltage across the energy storage filter capacitor EC1 is higher than the driving voltage required by the LED lamp set 200 for steady-state operation, the current flowing through the second switch tube Q2 and the second sampling resistor Rcs2 becomes larger, that is, the voltage across the second terminal of the second switch tube (i.e., the source of the MOS transistor) rises, so that the voltage across the first capacitor C3 connected to the control terminal of the second switch tube Q2 (i.e., the gate of the MOS transistor) decreases, that is, the on-state voltage of the control terminal of the second switch tube Q2 (i.e., the gate of the MOS transistor) decreases, so that the equivalent impedance of the second switch tube Q2 becomes relatively larger, and the voltage across the first terminal of the second switch tube Q2 (i.e., the drain of the MOS transistor) becomes larger accordingly. The voltage across the LED lamp set 200 is the difference between the voltage across the energy storage filter capacitor EC1 and the voltage across the second switch tube Q2 and the voltage across the second sampling resistor Rcs2, that is, V _ LED is V _ EC1-V _ Q2-V _ Rcs2, since the value of V _ Rcs2 is small and can be ignored, the voltage across the LED lamp set 200 can be regarded as the voltage across the energy storage filter capacitor EC1 and the voltage across the second switch tube Q2. If the stable no stroboscopic output of the LED lamp group 200 is to be kept, it is only necessary to ensure that the driving voltages at the two ends of the LED lamp group 200 are kept constant, and there is no obvious fluctuation, and the voltage at the first end (i.e., the drain of the MOS transistor, connected to the negative end of the LED lamp group 200) of the second switch transistor Q2 and the voltage at the positive end of the LED lamp group 200 keep the working mechanism of positive feedback following, that is, the ripple of the LED driving current can be eliminated in different input voltage ranges by the LED driving circuit through the ripple eliminating module 140, so as to achieve the driving effect of no stroboscopic output.

Referring to fig. 4 and 5, fig. 4 is a schematic diagram of input current of a prior art LED driving circuit and waveforms of the LED driving circuit. Fig. 5 is a schematic diagram of the input current of the LED driving circuit and the waveform of the LED driving circuit according to the present invention. Where VAC represents the input voltage, Iin represents the input current, I _ LED represents the operating current, and T represents time.

As can be seen from fig. 4, when the input voltage is high or low, the output current of the LED driving circuit (i.e., the current flowing through the LED lamp set) contains a large number of power frequency ripple components. As can be seen from fig. 5, with the LED driving circuit 1000 according to the embodiment of the present invention, the output current is substantially linear, that is, the LED driving circuit 1000 effectively eliminates the power frequency ripple component in the output current. Thus, the LED driving circuit 1000 according to the present invention has a high power factor, and is compatible with the LED lamp set 200 without stroboflash when the LED lamp set 200 is turned on, and the current flowing through the LED lamp set 200 is constant.

As shown in fig. 6, based on the same inventive concept, an embodiment of the present invention further provides an LED constant current driver 3000. Which includes the LED driving circuit 1000 according to any of the embodiments of the present invention. The LED constant current driver 3000 may be adapted to output power less than 25W and meet the requirements of strobe and power factor calibration.

In addition, the embodiment of the invention also provides the lighting equipment. As shown in fig. 6, the lighting device 5000 includes an LED constant current driver 3000 and an LED lamp group 200 connected to the LED constant current driver 3000.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The LED driving circuit, the LED constant current driver and the lighting device provided by the embodiment of the present invention are described in detail above, a specific example is applied in the present disclosure to explain the principle and the implementation of the present invention, and the description of the above embodiment is only used to help understanding the technical scheme and the core idea of the present invention; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. An LED drive circuit electrically connected with an LED lamp bank, the LED drive circuit comprising: the device comprises a rectifying module, an energy storage filter capacitor, a sampling module, a control module and a ripple wave eliminating module, wherein the rectifying module is used for rectifying input voltage; the sampling module is used for sampling the voltage output by the rectifying module so as to output a feedback signal to the control module; the energy storage filter capacitor and the control module are connected between the rectifying module and the ground in series, and the energy storage filter capacitor is used for charging and storing energy in the input current on-time and providing driving current for the LED lamp set in the input current off-time; the control module is electrically connected with the sampling module and used for controlling the current of the LED lamp set according to a feedback signal and a current signal on a first sampling resistor in the control module and controlling the conduction time and the charging current of the energy storage filter capacitor; the ripple eliminating module is connected with the LED lamp bank in series and then connected with the energy storage filter capacitor in parallel, and the ripple eliminating module is used for controlling the current of the LED lamp bank and eliminating the ripple current.

2. The LED driving circuit according to claim 1, wherein the sampling module is connected in series between the rectifying module and ground.

3. The LED driving circuit according to claim 1, wherein an input terminal of the sampling module is connected between the LED lamp set and the ripple cancellation module, and an output terminal of the sampling module is connected to the control module.

4. The LED driving circuit according to claim 1, wherein the sampling module comprises a first voltage dividing resistor and a second voltage dividing resistor connected in series, and the first voltage dividing resistor and the second voltage dividing resistor are used for dividing the voltage output by the rectifying module.

5. The LED driving circuit according to claim 1 or 4, wherein the sampling module further comprises a two-stage RC filter circuit for eliminating power frequency ripple noise of the rectified input voltage.

6. The LED driving circuit according to claim 5, wherein the RC filter circuit comprises a first filter resistor, a second filter resistor, a first filter capacitor and a second filter capacitor; the first end of the first filter resistor is connected with a common node of the first divider resistor and the second divider resistor, and the second end of the first filter resistor is respectively connected with the first end of the second filter resistor and the first end of the first filter capacitor; a first end of the second filter resistor is connected with a first end of the first filter capacitor, and a second end of the second filter resistor is respectively connected with an input end of the control module and a first end of the second filter capacitor; and the second end of the first filter capacitor and the second end of the second filter capacitor are both grounded.

7. The LED driving circuit according to claim 1, wherein the control module further comprises a first current source, a first operational amplifier, a first switching tube, and a third voltage dividing resistor; the input end of the first current source is connected with the input end of the control module, and the output end of the first current source is respectively connected with the inverting input end of the first operational amplifier and the first end of the third voltage dividing resistor; the positive phase input end of the first operational amplifier is used for receiving a reference voltage, and the output end of the first operational amplifier is connected with the control end of the first switching tube; a first end of the third voltage-dividing resistor is connected with an inverting input end of the first operational amplifier, and a second end of the third voltage-dividing resistor is respectively connected with a first end of the first switching tube and a first end of the first sampling resistor; the first end of the first switching tube is connected with the first end of the first sampling resistor, and the second end of the first switching tube is connected with the energy storage filter capacitor; the second end of the first sampling resistor is grounded.

8. The LED driving circuit according to claim 1, wherein the ripple elimination module comprises a second switching tube, a second sampling resistor and a first capacitor; the first end of the second switch tube is connected with the LED lamp group, the second end of the second switch tube is connected with the first end of the second sampling resistor, and the control end of the second switch tube is connected with the first end of the first capacitor; and the second end of the second sampling resistor is connected with the second end of the first capacitor.

9. The LED driving circuit according to claim 8, wherein the ripple cancellation module further comprises a zener diode and a first resistor; the cathode of the voltage stabilizing diode and the first end of the first resistor are both connected with the first end of the second switch tube; and the anode of the voltage stabilizing diode and the second end of the first resistor are both connected with the control end of the second switching tube.

10. The LED driving circuit according to claim 1, wherein the rectifying module, the energy storage filter capacitor, the control module and ground are connected in series in sequence.

11. The LED driving circuit according to claim 1, wherein the rectifying module, the control module, the energy storage filter capacitor and ground are connected in series in sequence.

12. An LED constant current driver, characterized by comprising the LED driving circuit according to any one of claims 1 to 11.

13. A lighting device, characterized by comprising the LED constant current driver of claim 12 and a LED lamp group electrically connected to the LED constant current driver.