LED linear constant-current driving circuit and LED lighting circuit

Abstract

The invention belongs to the technical field of LED drive circuits, and particularly relates to an LED linear constant-current drive circuit and an LED lighting circuit. An LED linear constant-current driving circuit comprises a power supply unit and an LED constant-current control unit. The system further comprises an energy storage unit and an energy storage control unit. The energy storage control unit is used for controlling the energy storage unit to charge with a first current and a second current in sequence according to the collected rectified voltage under the condition that the amplitude of the rectified voltage is greater than a first preset threshold until the amplitude of the rectified voltage is less than a second preset threshold, and the first current is greater than the second current. By controlling the charging and discharging of the energy storage unit, the energy storage unit can be controlled to be charged at a relatively large first current and then to be charged at a relatively small second current, and when the effective value of the rectified voltage is relatively low, the working current of the LED light-emitting unit can be maintained to be constant in an auxiliary manner, so that stroboflash of the LED light-emitting unit at low voltage is avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of LED drive circuits, and in particular to LED linear constant current drive circuits and LED lighting circuits. Background Art

[0002] At present, with the continuous popularization of LED lighting and the continuous development of technology, LED lighting has gradually entered all aspects of life. At the same time, the requirements of the LED lighting industry are getting higher and higher. At present, certification specifications such as high power factor (PF) and no flicker have been proposed. The existing constant current drive technology and linear constant current system have already met the relevant certification requirements, such as Figure 1 The existing constant current drive circuit shown, for example, has related technical records in the public patent documents, such as the publication number: CN214315687U, the name is: a linear constant current drive circuit and a linear constant current system; the publication number: CN212064422U, the name is: LED constant current drive circuit and LED lighting device. The high power factor constant current drive control system currently available on the market has a power fluctuation rate angle within the rated input voltage range of 200 to 240VAC, low voltage power supply, low input power, and a minimum input voltage of 200VAC. The current on the LED lamp still has a fluctuating current, which cannot be completely flicker-free, and does not meet the latest EU Energy Efficiency Directive (EU ERP) and my country's new national standard for LED light source products.

[0003] Therefore, the traditional technical solution still has the problem of flicker when the power supply is low voltage. Summary of the invention

[0004] The purpose of this application is to provide a waveform control circuit, aiming to solve the flicker problem existing in the traditional 200V low-voltage power supply.

[0005] The first aspect of an embodiment of the present application provides an LED linear constant current drive circuit for driving an LED light-emitting unit, comprising: a power supply unit for rectifying an input current to provide a rectified voltage to the LED light-emitting unit; an LED constant current control unit for maintaining a constant current flowing through the LED light-emitting unit; and further comprising: an energy storage unit and an energy storage control unit; the input end of the LED light-emitting unit is grounded in turn through the energy storage unit and the energy storage control unit, the energy storage control unit being provided with a signal sampling end for collecting the rectified voltage; the energy storage control unit being used to control the energy storage unit to charge with a first current and a second current in turn according to the collected rectified voltage, when the amplitude of the rectified voltage is greater than a first preset threshold value, until the amplitude of the rectified voltage is less than a second preset threshold value, wherein the first current is greater than the second current.

[0006] In one embodiment, the energy storage control unit includes: a constant current control module and a reference adjustment module; the first end of the energy storage unit is connected to the input end of the LED light-emitting unit, and the second end of the energy storage unit is grounded through the constant current control module; the reference adjustment module is connected to the signal sampling end through a sampling resistor, and the constant current control module is connected to the reference adjustment module, the sampling resistor is used to generate a working current based on the voltage of the signal sampling end, and the reference adjustment module is used to send an adjustment signal to the constant current control module according to the working current; the constant current control module is used to control the working state of the energy storage unit and the charging current size according to the adjustment signal.

[0007] In one embodiment, the reference adjustment module includes a reference voltage setting circuit, the reference voltage setting circuit is used to receive the working current, or the reference adjustment module is provided with an amplifier circuit for amplifying the working current; the amplifier circuit amplifies the working current and transmits it to the reference voltage setting circuit, the reference voltage setting circuit forms a first reference voltage and a second reference voltage; the reference voltage setting circuit selects one of the first reference voltage and the second reference voltage as a main reference voltage according to the working current or the amplified working current, and transmits the main reference voltage to the constant current control module; the constant current control module is used to generate the first current or the second current according to the main reference voltage.

[0008] In one embodiment, the amplifier circuit includes a first current mirror and a second current mirror; the first current mirror is electrically connected to the sampling resistor, and is used to generate a first mirror current based on the working current; the second current mirror is electrically connected to the first current mirror, and is used to receive the first mirror current and generate a second mirror current, and the second current mirror is connected to the reference voltage setting circuit, and transmits the second mirror current to the reference voltage setting circuit.

[0009] In one embodiment, the reference voltage setting circuit includes: a comparison unit and a reference voltage selection unit, the comparison unit is provided with two input terminals, one of which is used to receive the amplified working current, and the other input terminal of the comparison unit is connected to a threshold current circuit and receives the threshold current output by the threshold current circuit; the reference voltage selection unit is provided with two input terminals, an output terminal and a control terminal, the two input terminals are respectively connected to the reference voltage providing circuit, the control terminal is connected to the output terminal of the comparison unit, and the reference voltage selection unit selects one of the input terminals to be connected to the output terminal according to the output value of the comparison unit.

[0010] In one embodiment, the reference voltage setting circuit further includes a third current mirror, which is used to receive the second mirror current and generate a third mirror current; the output end of the third current mirror is connected to an input end of the comparison unit.

[0011] In one embodiment, the reference regulation module also includes a constant power regulation circuit, which includes: a fourth current mirror, a fifth current mirror and a constant power conversion circuit; the fourth current mirror is electrically connected to the sampling resistor, and is used to receive the working current and generate a fourth mirror current; the fifth current mirror is electrically connected to the fourth current mirror, and is used to receive the fourth mirror current and generate a fifth mirror current; the constant power conversion circuit receives the fifth mirror current and generates a secondary reference voltage, and provides the secondary reference voltage to the constant current control module, and the constant current control module controls the output current according to the changes of the received main reference voltage and the secondary reference voltage.

[0012] In one embodiment, the constant power conversion circuit includes: a sixth current mirror and a seventh current mirror, the sixth current mirror is electrically connected to the fifth current mirror, for receiving the fifth mirror current and generating a sixth mirror current; the seventh current mirror is electrically connected to the sixth current mirror, for receiving the sixth mirror current and generating a seventh mirror current; the output end of the seventh current mirror is connected to the constant current control module.

[0013] In one embodiment, the constant current control module includes an operational amplifier and a field effect transistor, the non-phase input terminal of the operational amplifier is connected to the main reference voltage, and the inverting input terminal of the operational amplifier is connected to the secondary reference voltage; the inverting input terminal is connected to the source of the field effect transistor through a feedback resistor; the output terminal of the operational amplifier is connected to the gate of the field effect transistor, the drain of the field effect transistor is connected to the energy storage unit, and the output terminal of the operational amplifier is grounded through an adjustment resistor.

[0014] A second aspect of an embodiment of the present application provides an LED lighting circuit, comprising the above-mentioned LED linear constant current drive circuit, and also comprising an LED light-emitting unit, wherein the LED light-emitting unit is connected to the LED linear constant current drive circuit.

[0015] The beneficial effect of the embodiments of the present invention compared with the prior art is that by controlling the charging and discharging of the energy storage unit, the energy storage unit can be controlled to be charged with a larger first current first, and then controlled to be charged with a smaller second current. When the effective value of the rectified voltage is low, the working current of the LED light-emitting unit can be assisted to maintain constant, so as to avoid the LED light-emitting unit from flickering at low voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1It is a block diagram of a traditional LED constant current drive circuit structure; for ease of understanding, the LED light-emitting unit is also shown;

[0017] Figure 2 A schematic diagram of a module block diagram of an LED linear constant current drive circuit shown in an embodiment;

[0018] Figure 3 It is a schematic block diagram of another module of an LED linear constant current driving circuit of an embodiment;

[0019] Figure 4 A circuit diagram of a LED linear constant current drive circuit shown in an embodiment;

[0020] Figure 5 A circuit diagram of another LED linear constant current driving circuit shown in an embodiment;

[0021] Figure 6 A circuit diagram of a reference adjustment module shown in an embodiment;

[0022] Figure 7 A waveform diagram of an LED linear constant current driving circuit shown in an embodiment;

[0023] Figure 8 The waveform diagram of the second LED linear constant current driving circuit shown in the embodiment;

[0024] Fig. 9 This is a waveform diagram of a third LED linear constant current driving circuit shown in the embodiment;

[0025] Fig.10 A schematic diagram of a reference voltage setting circuit shown in an embodiment;

[0026] Fig.11 A schematic diagram of a constant power conversion circuit and a constant current control module shown in an embodiment;

[0027] Fig.12 A circuit diagram of an LED constant current control unit shown in an embodiment;

[0028] The accompanying drawings are marked as follows:

[0029] 1——power supply unit; 2——LED light emitting unit; 3——energy storage control unit; 4——LED constant current control unit; 5——energy storage unit;

[0030] 31——reference adjustment module; 32——constant current control module;

[0031] 311 - first current mirror; 312 - second current mirror; 313 - reference voltage setting circuit; 314 - fourth current mirror; 315 - fifth current mirror; 316 - constant power conversion circuit;

[0032] 3131——third current mirror; 3132——reference voltage selection unit; 3133——threshold current circuit; 3134——comparison unit; 3161——sixth current mirror; 3162——seventh current mirror. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0035] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] Figure 2 Shows a preferred embodiment of the present application ( Figure 2 FIG. 1 shows a schematic diagram of a structural block diagram of an LED linear constant current driving circuit provided in the first embodiment of the present application. For the sake of convenience, only the parts related to the present embodiment are shown, which are described in detail as follows:

[0038] An LED linear constant current driving circuit is used to drive an LED light emitting unit 2 to solve the problem that when the current low voltage 200V power supply is used, the constant current driving circuit still has a flickering problem when driving the LED light emitting unit 2 to work. For example, Figure 2 As shown, the LED constant current drive circuit includes a power supply unit 1, an LED constant current control unit 4, an energy storage unit 5 and an energy storage control unit 3. The power supply unit 1 is connected to the LED light-emitting unit 2 and the energy storage control unit 3 respectively. The power supply unit 1 can supply power to the LED light-emitting unit 2. Specifically, the power supply unit 1 can rectify the input current to provide a rectified voltage to the LED light-emitting unit 2. The LED constant current control unit 4 is connected in series with the LED light-emitting unit 2. Specifically, the LED constant current control unit 4 and the LED light-emitting unit 2 are connected in series between the power supply unit 1 and the ground. The input end of the LED light-emitting unit 2 is grounded through the energy storage unit 5 and the energy storage control unit 3 in turn, and the energy storage control unit 3 is provided with a signal sampling end. The signal sampling end is used to collect the rectified voltage. The signal sampling end can be connected to the output end of the LED light-emitting unit 2, and can also be connected to the input end of the LED light-emitting unit 2. See Figure 2 , Figure 3 . It can be understood that the LED light-emitting unit 2 will produce a certain voltage drop, and the waveform of the rectified voltage collected at the output end of the LED light-emitting unit 2 is overall shifted down by a certain voltage compared with the waveform of the rectified voltage collected at the input end of the LED light-emitting unit 2. The energy storage control unit 3 obtains the rectified voltage through the signal sampling end. The energy storage control unit 3 can control the energy storage unit 5 to charge or discharge the LED light-emitting unit 2 based on the rectified voltage according to the rectified voltage. Specifically, the energy storage control unit 3 can control the energy storage unit 5 to charge with the first current and the second current in sequence when the amplitude of the rectified voltage is greater than the first preset threshold, until the amplitude of the rectified voltage is less than the second preset threshold, wherein the first current is greater than the second current. The LED light-emitting unit 2 is kept in a constant current working state. At the same time, the LED light-emitting circuit can achieve the purpose of no flicker while achieving a high power factor. In some embodiments, the first preset threshold may be equal to the second preset threshold.

[0039] During operation, by controlling the charging and discharging of the energy storage unit 5, the energy storage unit 5 can be controlled to be charged with a larger first current first, and then controlled to be charged with a smaller second current. When the effective value of the rectified voltage is low, it can assist in maintaining the working current of the LED light-emitting unit 2 constant to avoid the LED light-emitting unit 2 from flickering at low voltage, such as 200VAC.

[0040] See also Figure 4 , Figure 5, the energy storage control unit 3 includes: a constant current control module 32 and a reference adjustment module 31. Among them, the first end of the energy storage unit 5 is connected to the input end of the LED light-emitting unit 2, and the second end of the energy storage unit 5 is grounded through the constant current control module 32. The reference adjustment module 31 is connected to the signal sampling end through the sampling resistor R0. The sampling resistor R0 is used to generate a working current based on the voltage of the signal sampling end. It can be understood that the magnitude of the working current is positively correlated with the magnitude of the rectified voltage. The reference adjustment module 31 is used to receive the working current of the LED light-emitting unit 2 and send an adjustment signal to the constant current control module 32 according to the working current. The constant current control module 32 is connected to the energy storage unit 5 and the reference adjustment module 31. The constant current control module 32 receives the adjustment signal, controls the output current according to the adjustment signal, and adjusts the working state of the energy storage unit 5 and the charging current.

[0041] For example, Figure 4 , 5 As shown, the energy storage unit 5 can use an electrolytic capacitor E1, one end of the electrolytic capacitor E1 is connected to the output end of the power supply unit 1 and the input end of the LED light-emitting unit 2, and the other end of the electrolytic capacitor E1 is grounded through the constant current control module 32. The reference adjustment module 31 obtains the working current I_0 of the LED light-emitting unit 2 through the signal sampling end. The reference adjustment module 31 is provided with two reference voltages and two current thresholds corresponding to the first preset threshold and the second preset threshold, respectively, wherein the two current thresholds may be equal. Exemplarily, the reference adjustment module 31 may compare the received working current I_0 with the current threshold I1, or amplify the working current I_0 and then compare it with the current threshold I1. When the working current I_0 is greater than the current threshold I1, the first reference voltage Vref1_1 and the second reference voltage Vref1_2 are output in sequence. It should be noted that when the first reference voltage Vref1_1 and the second reference voltage Vref1_2 are received, the constant current control module 32 may be turned on and the current flowing through the constant current control module 32 may be based on the first reference voltage Vref1_1 and the second reference voltage Vref1_2. After the constant current control module 32 is turned on, the energy storage unit 5 may be charged.

[0042] Specifically, when the constant current control module 32 receives the first reference voltage Vref1_1, the constant current control module 32 can control the energy storage unit 5 to be charged with the first current; when the constant current control module 32 receives the second reference voltage Vref1_2, the constant current control module 32 can control the energy storage unit 5 to be charged with the second current.

[0043] In some embodiments, the energy storage control unit 3 may control the energy storage unit 5 to switch from charging with the first current to charging with the second current when the amplitude of the rectified voltage changes from less than the third preset threshold to greater than the third preset threshold.

[0044] Specifically, the reference adjustment module 31 compares the received working current I_0 with the current threshold I0, or amplifies the working current I_0 and then compares it with the current threshold I0.

[0045] According to the different comparison results, two reference voltages are outputted respectively. For example, when the working current I_0 or the amplified working current I_0 is less than the current threshold I0 and greater than the current threshold I1, the reference adjustment module 31 outputs the first reference voltage Vref1_1. When the working current I_0 or the amplified working current I_0 is greater than or equal to the current threshold I0, the reference adjustment module 31 outputs the second reference voltage Vref1_2 until the working current I_0 is less than the current threshold I1. The constant current control module 32 then adjusts the constant current size according to the received reference voltage. For example, the constant current control module 32 receives the first reference voltage Vref1_1 and generates the first current I_1. The constant current control module 32 receives the second reference voltage Vref1_2 and generates the second current I_2. Exemplarily, the power supply unit 1 can use a rectifier circuit connected to the mains to power the LED constant current control unit 4 through the rectifier circuit. The power supply unit 1 can also use other styles of DC sources.

[0046] The energy storage control unit 3 is used to discharge the LED light emitting unit 2 through the energy storage unit 5 when the output voltage of the power supply unit 1 is less than or equal to the working voltage of the LED light emitting unit 2, so as to maintain the constant working current of the LED light emitting unit 2. The constant current control module 32 is used to control the charging and discharging of the energy storage unit 5, and the reference adjustment module 31 sends a current adjustment signal to the constant current control module 32 by collecting the working current of the LED light emitting unit 2, so that the constant current control module 32 adjusts the charging current of the energy storage unit 5 in the circuit.

[0047] Preferably, the energy storage unit includes an electrolytic capacitor E1 , a positive electrode of the electrolytic capacitor E1 is connected to the output end of the power supply unit 1 , and a negative electrode of the electrolytic capacitor E1 is connected to the constant current control module 32 .

[0048] When working, the constant current control module 32 adjusts the current of the output electrolytic capacitor E1 according to the received reference voltage, so that the electrolytic capacitor E1 stores enough charge energy when discharging. In specific implementation, when the voltage provided by the power supply unit 1 is less than the working voltage of the LED light-emitting unit 2, the electrolytic capacitor E1 discharges to the LED light-emitting unit 2 to ensure that the LED light-emitting unit 2 works at a constant current. When the voltage provided by the power supply unit 1 is greater than or equal to the working voltage of the LED light-emitting unit 2, the power supply unit 1 charges the electrolytic capacitor E1. Figure 7As shown, in the first charging stage t1-t2 time period, the reference adjustment module 31 outputs the first reference voltage Vref1_1 to the constant current control module 32, and the constant current control module 32 controls the output current to be I_1. In the second charging stage, the reference adjustment module 31 outputs the second reference voltage Vref1_2 to the constant current control module 32, and the constant current control module 32 controls the output current to be I_2. It can be achieved that within one line network cycle, the phase cycle time of the AC input current from no current to peak current is <65°.

[0049] See also Figure 4 , Figure 5 as well as Figure 6 The energy storage control unit 3 is provided with a sampling resistor R0, and one end of the sampling resistor R0 is connected to the signal sampling end. The reference adjustment module 31 includes: an amplifier circuit for amplifying the working current and a reference voltage setting circuit 313. The amplifier circuit includes a first current mirror 311 and a second current mirror 312. The first current mirror 311 is electrically connected to the sampling resistor R0, and is used to receive the sampled working current and generate a first mirror current. The second current mirror 312 is electrically connected to the first current mirror 311, and is used to receive the first mirror current and generate a second mirror current. The second current mirror 312 is connected to the reference voltage setting circuit 313, and transmits the second mirror current to the reference voltage setting circuit 313.

[0050] Exemplarily, the working current obtained by the first current mirror 311 through the sampling resistor R0 is the working current Iin1. In this embodiment, the first current mirror 311 and the second current mirror 312 amplify the working current Iin1 in turn, and output the current IA1 to the outside. The current IA1 is transmitted to the reference voltage setting circuit 313. The reference voltage setting circuit 313 outputs the reference voltage Vref1_1 or the reference voltage Vref1_2 to the constant current control module 32 according to the size of the output current IA1.

[0051] See also Fig.10 The reference voltage setting circuit 313 includes: a comparison unit 3134 and a reference voltage selection unit 3132. The comparison unit 3134 is provided with two input terminals, one of which is used to receive the amplified working current (i.e., the current IA1), and the other input terminal of the comparison unit 3134 is used to receive the threshold current. In a specific setting, the input terminal is connected to the threshold current circuit 3133, and the threshold current is output to the comparison unit 3134 through the threshold current circuit 3133. The reference voltage selection unit 3132 is provided with two input terminals, an output terminal and a control terminal. The two input terminals are respectively connected to the reference voltage providing circuit, and the control terminal is connected to the output terminal of the comparison unit 3134.

[0052] The comparison unit 3134 receives the threshold current and the amplified working current through two input terminals, respectively, and compares them, and sends the comparison result in the form of current to the reference voltage selection unit 3132. The reference voltage selection unit 3132 selects one of the input terminals to be connected to the output terminal according to the comparison result, and outputs the corresponding reference voltage. It can be understood that the two reference voltage providing circuits can provide the first reference voltage Vref1_1 and the second reference voltage Vref1_2 respectively.

[0053] Preferably, the reference voltage setting circuit 313 further includes a third current mirror 3131 , which is used to receive the second mirror current and generate a third mirror current. The output end of the third mirror current is connected to an input end of the comparison unit 3134 .

[0054] In practical applications, the third current mirror 3131 can be set as needed. It is used to amplify the collected working current again. The comparison unit 3134 compares the amplified working current with the threshold current, and transmits the comparison result information to the reference voltage selection unit 3132. The reference voltage selection unit 3132 selects one of the reference voltages according to the comparison result and outputs it to the constant current control module 32.

[0055] For example, Fig.10 As shown, in this embodiment, a third current mirror 3131 is designed, and the third current mirror 3131 amplifies the output current IA1 again, such as amplifying K5 times. The comparison unit 3134 can be a comparator, and one input end of the comparator receives the output current of the third current mirror 3131. The threshold current circuit 3133 can be of various types, such as a voltage divider circuit connected between a power supply and a ground, and an intermediate potential end of the voltage divider circuit outputs a threshold current to the outside through a predetermined resistor. For example, Fig.10 As shown, in this embodiment, the threshold current circuit 3133 includes a MOS transistor, the source of the MOS transistor is connected to the power supply VDD, the drain of the MOS transistor is connected to an input terminal of the comparator, and the gate of the MOS transistor is connected to a fixed voltage terminal Vb. When the threshold current I0 is greater than or less than the output current of the third current mirror 3131, the comparator outputs two different current signals to the reference comparison selection circuit.

[0056] The reference voltage providing circuit can be the prior art, such as using a voltage divider circuit between the power supply and the ground, and one of the intermediate potential ends of the voltage divider circuit outputs a reference voltage to the outside. The two reference voltage providing circuits respectively provide two reference voltages: a first reference voltage Vref1_1 and a second reference voltage Vref1_2. The reference voltage setting circuit 313 outputs a main reference voltage Vref1 to the outside. The control end of the reference voltage selection unit 3132 receives the current signal of the comparison unit 3134, and outputs a reference voltage Vref1_1 or a reference voltage Vref1_2 to the outside according to the current signal, that is, the main reference voltage Vref1 is one of the first reference voltage Vref1_1 and the second reference voltage Vref1_2. The reference voltage selection unit 3132 outputs two different reference voltages to the outside. The constant current control module 32 outputs different working currents according to different reference voltages.

[0057] See also Figure 6 The reference adjustment module 31 also includes a constant power adjustment circuit, which includes: a fourth current mirror 314, a fifth current mirror 315 and a constant power conversion circuit 316. The fourth current mirror 314 is electrically connected to the sampling resistor R0, and is used to receive the sampled working current and generate a fourth mirror current. The fourth current mirror 314, to which the fifth current mirror 315 is electrically connected, is used to receive the fourth mirror current and generate a fifth mirror current. The constant power conversion circuit 316 receives the fifth mirror current and generates a secondary reference voltage Vref2, and provides the secondary reference voltage Vref2 to the constant current control module 32. The current output by the constant current control module 32 controls the output current size according to the changes of the received main reference voltage Vref1 and the secondary reference voltage Vref2.

[0058] Before the constant power regulation circuit is set, the current output by the constant current control module 32 is only controlled by the magnitude of the main reference voltage Vref1, that is, the magnitude of the charging current of the electrolytic capacitor. Since the main reference voltage is based on the first reference voltage Vref_1 or the second reference voltage Vref_2, the output current of the constant current control module 32 is step-like, see Figure 7 After the constant power regulation circuit is introduced, the current output by the constant current control module 32 is continuous while maintaining the constant power output, and can be linear or nonlinear. Figure 8 , Fig. 9The fourth current mirror 314 receives the working current. To distinguish it from the working current Iin1 and facilitate understanding, the working current is set to the working current Iin2. The fourth current mirror 314 and the fifth current mirror 315 amplify the working current Iin2 in turn and form the current IA2. The current IA2 generates the secondary reference voltage Vref2 through the constant power conversion circuit 316 inside the reference adjustment module 31. The secondary reference voltage Vref2 is provided to the constant current control module 32. The current generated by the constant current control module 32 changes with the working current IA2 generated by the working current Iin2. See Figure 6 .

[0059] See also Fig.11 The constant power conversion circuit 316 includes: a sixth current mirror 3161 and a seventh current mirror 3162, the sixth current mirror 3161 is electrically connected to the fifth current mirror 315, and is used to receive the fifth mirror current and generate the sixth mirror current. The seventh current mirror 3162 is electrically connected to the sixth current mirror 3161, and is used to receive the sixth mirror current and generate the seventh mirror current. The output end of the seventh current mirror 3162 is connected to the constant current control module 32.

[0060] See also Fig.11 The constant current control module 32 includes an operational amplifier and a field effect tube. The positive input terminal of the operational amplifier is connected to the main reference voltage Vref1, and the inverting input terminal of the operational amplifier is connected to the secondary reference voltage Vref2. The inverting input terminal is connected to the source of the field effect tube through the feedback resistor R1. The output terminal of the operational amplifier is connected to the gate of the field effect tube, the drain of the field effect tube is connected to the energy storage unit 5 (the negative electrode of the electrolytic capacitor E1), and the output terminal of the operational amplifier is grounded through the adjustment resistor R2.

[0061] like Fig.11 As shown, the current IA2 passes through the constant power regulation circuit to form the current IA3. The constant power regulation circuit is connected to the constant current control module 32 through the control line S1. The control line S1 is connected to the inverting input terminal of the operational amplifier of the constant current control module 32. The constant current control module 32 outputs the current IA4 to the outside. The change of the current IA3 is proportional to the change of the current IA4 output by the constant current control module 32. The proportional relationship is: IA4 = (Vref1-IA3*R1) / R2. Among them, IA4 is the current value of the current IA4, Vref1 is the voltage value of the main reference voltage Vref1, IA3 is the current value of the current IA3, R1 is the resistance value of the feedback resistor R1, and R2 is the resistance value of the adjustment resistor R2. Among them, IA3*R1 is the secondary reference voltage Vref2.

[0062] In combination with the above, during the line network cycle, when the output voltage of the power supply unit 1 is greater than the lamp voltage, the electrolytic capacitor is charged, and the charging current IA4 is controlled by the constant current control module 32. Under the low voltage 200Vac input, the current waveform generated by the constant current control module 32 is as follows: Figure 7 When the electrolytic capacitor is in charging mode, because the current I_1 can be set greater than the current I_2, the electrolytic capacitor E1 can store more charging energy during the time t1 to t2, thereby increasing the power under 200Vac input. When the electrolytic capacitor is in discharging mode, it can release more energy to the LED light-emitting unit 2, ensuring that the LED light-emitting unit 2 has a completely constant current.

[0063] Under high voltage 240Vac input, the current waveform generated by the constant current control module 32 is as follows: Fig. 9 When the electrolytic capacitor is in charging mode, the charging current of the electrolytic capacitor E1 can be set to 0 during the time t3 to t4 to reduce the useless work generated in this stage and reduce the power under 240Vac input.

[0064] By setting the waveform size of the specific solution, it can be achieved that within one line network cycle, the phase cycle time of the AC input current from no current to peak current is <65°, meeting the requirements of existing LED certification indicators. The embodiment can reduce the input power change rate under 200-240Vac input, and the constant power effect is better. At the same time, it is ensured that the LED light source or lamp made by this patent has a higher power factor and no flicker under the rated input voltage of the LED.

[0065] An LED lighting circuit comprises the above-mentioned LED linear constant current driving circuit and an LED light emitting unit 2, wherein the LED light emitting unit 2 is connected to the LED linear constant current driving circuit.

[0066] The LED light emitting unit 2 can be a plurality of LEDs connected in series, in parallel or in mixed series. Fig.12 The LED constant current control unit 4 includes an operational amplifier INV1 and a field effect tube, and the non-phase input terminal of the operational amplifier is connected to the reference voltage Vref. The inverting input terminal is connected to the source of the field effect tube through a feedback resistor. The output terminal of the operational amplifier is connected to the gate of the field effect tube, the drain of the field effect tube is connected to a capacitor, and the output terminal of the operational amplifier is grounded through an adjustment resistor. The LED constant current control unit 4 can adopt a constant current source circuit, and the LED constant current control unit 4 can be a prior art.

[0067] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An LED linear constant current driving circuit for driving an LED light-emitting unit, comprising: A power supply unit, used for rectifying an input current to provide a rectified voltage to the LED light-emitting unit; An LED constant current control unit, used to maintain a constant current flowing through the LED light-emitting unit; It is characterized by: further comprising: an energy storage unit and an energy storage control unit; The input end of the LED light-emitting unit is grounded through the energy storage unit and the energy storage control unit in sequence, and the energy storage control unit is provided with a signal sampling end, and the signal sampling end is used to collect the rectified voltage; The energy storage control unit is used to control the energy storage unit to charge with a first current and a second current in sequence according to the collected rectified voltage, when the amplitude of the rectified voltage is greater than a first preset threshold, until the amplitude of the rectified voltage is less than a second preset threshold, wherein the first current is greater than the second current.

2. The LED linear constant current driving circuit according to claim 1, characterized in that: The energy storage control unit includes: a constant current control module and a reference adjustment module; the first end of the energy storage unit is connected to the input end of the LED light-emitting unit, and the second end of the energy storage unit is grounded through the constant current control module; the reference adjustment module is connected to the signal sampling end through a sampling resistor, and the constant current control module is connected to the reference adjustment module, the sampling resistor is used to generate a working current based on the voltage of the signal sampling end, and the reference adjustment module is used to send an adjustment signal to the constant current control module according to the working current; the constant current control module is used to control the working state of the energy storage unit and the charging current size according to the adjustment signal.

3. The LED linear constant current driving circuit as claimed in claim 2, characterized in that: The reference adjustment module includes a reference voltage setting circuit, and the reference voltage setting circuit is used to receive the working current, or the reference adjustment module is provided with an amplification circuit for amplifying the working current; The amplifier circuit amplifies the operating current and transmits it to the reference voltage setting circuit, and the reference voltage setting circuit forms a first reference voltage and a second reference voltage; The reference voltage setting circuit selects one of the first reference voltage and the second reference voltage as a main reference voltage according to the working current or the amplified working current, and transmits the main reference voltage to the constant current control module; The constant current control module is used to generate the first current or the second current according to the main reference voltage.

4. The LED linear constant current driving circuit as claimed in claim 3, characterized in that: The amplifying circuit comprises a first current mirror and a second current mirror; the first current mirror is electrically connected to the sampling resistor and is used to generate a first mirror current based on the working current; The second current mirror is electrically connected to the first current mirror, and is used to receive the first mirror current and generate a second mirror current. The second current mirror is connected to the reference voltage setting circuit, and transmits the second mirror current to the reference voltage setting circuit.

5. The LED linear constant current driving circuit as claimed in claim 4, characterized in that: The reference voltage setting circuit includes: a comparison unit and a reference voltage selection unit, the comparison unit is provided with two input terminals, one of which is used to receive the amplified working current, and the other input terminal of the comparison unit is connected to a threshold current circuit and receives the threshold current output by the threshold current circuit; the reference voltage selection unit is provided with two input terminals, an output terminal and a control terminal, the two input terminals are respectively connected to the reference voltage providing circuit, the control terminal is connected to the output terminal of the comparison unit, and the reference voltage selection unit selects one of the input terminals to be connected to the output terminal according to the output value of the comparison unit.

6. The LED linear constant current driving circuit as claimed in claim 5, characterized in that: The reference voltage setting circuit also includes a third current mirror, which is used to receive the second mirror current and generate a third mirror current; the output end of the third current mirror is connected to an input end of the comparison unit.

7. The LED linear constant current driving circuit according to any one of claims 3 to 6, characterized in that: The reference regulation module also includes a constant power regulation circuit, which includes: a fourth current mirror, a fifth current mirror and a constant power conversion circuit; the fourth current mirror is electrically connected to the sampling resistor, and is used to receive the working current and generate a fourth mirror current; the fifth current mirror is electrically connected to the fourth current mirror, and is used to receive the fourth mirror current and generate a fifth mirror current; the constant power conversion circuit receives the fifth mirror current and generates a secondary reference voltage, and provides the secondary reference voltage to the constant current control module, and the constant current control module controls the output current according to the changes of the received main reference voltage and the secondary reference voltage.

8. The LED linear constant current driving circuit according to claim 7, characterized in that: The constant power conversion circuit includes: a sixth current mirror and a seventh current mirror, the sixth current mirror is electrically connected to the fifth current mirror, and is used to receive the fifth mirror current and generate a sixth mirror current; the seventh current mirror is electrically connected to the sixth current mirror, and is used to receive the sixth mirror current and generate a seventh mirror current; the output end of the seventh current mirror is connected to the constant current control module.

9. The LED linear constant current driving circuit as claimed in claim 8, characterized in that: The constant current control module includes an operational amplifier and a field effect transistor, the non-inverting input terminal of the operational amplifier is connected to the main reference voltage, and the inverting input terminal of the operational amplifier is connected to the secondary reference voltage; The inverting input terminal is connected to the source of the field effect tube through a feedback resistor; the output terminal of the operational amplifier is connected to the gate of the field effect tube, the drain of the field effect tube is connected to the energy storage unit, and the output terminal of the operational amplifier is grounded through an adjustment resistor.

10. An LED lighting circuit, characterized in that: It comprises the LED linear constant current driving circuit as described in any one of claims 1 to 9; and also comprises an LED light-emitting unit, which is connected to the LED linear constant current driving circuit.

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