Constant power control circuit, method and LED linear constant power system

Abstract

The present application discloses a constant power control circuit, method and LED linear constant power system. The constant power control circuit includes: a peak voltage sampling and holding module, configured to collect the input terminal voltage and output a corresponding output voltage signal to a first voltage-controlled current source control module and a second voltage-controlled current source control module; a first voltage-controlled current source control module, configured to output a corresponding first current source signal to a constant current threshold control module; a second voltage-controlled current source control module, configured to output a corresponding second current source signal to the constant current threshold control module and an initial threshold setting module; an initial threshold setting module, configured to output a corresponding first threshold voltage signal to the constant current threshold control module; and a constant current threshold control module, configured to adjust the output drain current to stabilize the light-emitting power of the LED in the LED linear constant power system. The technical solution of the present application stabilizes the light-emitting power of the LED by adjusting the drain current.

Description

Technical Field

[0001] This application relates to the technical field of circuit - safe LED chip applications, and particularly to a constant - power control circuit, method, and LED linear constant - power system. Background Art

[0002] As a new type of green light source, LED lights have advantages such as high brightness, low energy consumption, and long lifespan. To ensure that LED lights can work normally and stably, a linear constant - current and constant - power scheme is usually adopted to control the current flowing through the LEDs. Currently, common LED linear constant - current and constant - power schemes include a rectifier circuit, a constant - current control module, and an LED load. However, the number of LED lights in the system load is strictly determined by the magnitude of the input voltage, and changes in the system voltage will cause changes in the output power of the entire drive device, thus affecting the unstable luminous power of the LED lights. Summary of the Invention

[0003] The main purpose of this application is to provide a constant - power control circuit, aiming to stabilize the luminous power of LED lights.

[0004] To achieve the above purpose, this application proposes a constant - power control circuit, which includes:

[0005] A peak - voltage sampling and holding module, which is used to collect the voltage at the input end to generate a corresponding input - voltage sampling signal, and according to the peak voltage of the input - voltage sampling signal and the voltage value of the input - voltage sampling signal in the previous time step, output a corresponding output - voltage signal to the first voltage - controlled current - source control module and the second voltage - controlled current - source control module;

[0006] The first voltage - controlled current - source control module, which is used to output a corresponding first current - source signal to the constant - current threshold control module according to a first preset threshold voltage and the output - voltage signal;

[0007] The second voltage - controlled current - source control module, which is used to output a corresponding second current - source signal to the constant - current threshold control module and the initial - threshold setting module according to a first preset threshold voltage and the output - voltage signal;

[0008] The initial - threshold setting module, which is used to output a corresponding first - threshold voltage signal to the constant - current threshold control module according to the second current - source signal and a second preset threshold voltage;

[0009] The constant - current threshold control module, which is used to adjust the drain current output by the constant - current threshold control module according to the first current - source signal, the second current - source signal, and the first - threshold voltage signal, so as to stabilize the luminous power of the LED lights in the LED linear constant - power system.

[0010] To achieve the above object, the present application also provides a constant power control circuit method, which is applied to the above constant power control circuit. The constant power control method includes:

[0011] If it is detected that an output voltage signal is generated, a corresponding first current source signal and a second current source signal are generated according to the output voltage signal and a first preset threshold voltage;

[0012] A corresponding first threshold voltage signal is generated according to the second current source signal and a second preset threshold voltage;

[0013] According to the first current source signal, the second current source signal and the first threshold voltage signal, the drain current output by the constant power control circuit is adjusted to stabilize the light-emitting power of the LED lamp in the LED linear constant power system.

[0014] To achieve the above object, the present application also proposes an LED linear constant power system. The LED linear constant power system includes a rectifier circuit, an LED load and the above constant power control circuit. For details, please refer to the above, and will not be elaborated here.

[0015] The technical solution of this application forms a constant power control circuit by setting a peak voltage sampling and holding module, a first voltage-controlled current source control module, a second voltage-controlled current source control module, an initial threshold setting module, and a constant current threshold control module. In this constant power control circuit, the peak voltage sampling and holding module is used to collect the voltage at the input end to generate a corresponding input voltage sampling signal, and according to the peak voltage of the input voltage sampling signal and the voltage value of the input voltage sampling signal in the previous time step, it outputs a corresponding output voltage signal to the first voltage-controlled current source control module and the second voltage-controlled current source control module; the first voltage-controlled current source control module is used to output a corresponding first current source signal to the constant current threshold control module according to a first preset threshold voltage and the output voltage signal; the second voltage-controlled current source control module is used to output a corresponding second current source signal to the constant current threshold control module and the initial threshold setting module according to the first preset threshold voltage and the output voltage signal; the initial threshold setting module is used to output a corresponding first threshold voltage signal to the constant current threshold control module according to the second current source signal and a second preset threshold voltage; the constant current threshold control module is used to adjust the drain current output by the constant current threshold control module according to the first current source signal, the second current source signal, and the first threshold voltage signal, so as to stabilize the light-emitting power of the LED in the LED linear constant power system. The technical solution of this application can adjust the drain current output by the system according to the magnitude of the input voltage. When the input voltage is large, the output drain current is reduced. When the input voltage is small, the output drain current is increased, which can avoid the situation that the change of the system input voltage will cause the output power of the entire driving device to change due to the constant drain current, thereby stabilizing the light-emitting power of the LED lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0017] Figure 1 It is a circuit function block diagram of an embodiment of the constant power control circuit in this application;

[0018] Figure 2 It is a circuit function block diagram of an embodiment of the constant power control circuit when the constant current threshold control module in this application is composed of a first operational amplifier, a first switching tube, a first resistor, and a second resistor;

[0019] Figure 3The circuit functional block diagram of an embodiment of the constant power control circuit when the peak voltage sampling and holding module in this application consists of a line network voltage sampling unit, a reset signal generation unit, a line network voltage peak sampling unit, a single machine signal generation unit, a voltage follower unit, and a voltage averaging unit;

[0020] Figure 4 The circuit functional block diagram of an embodiment of the constant power control circuit when the first voltage-controlled current source control module in this application consists of a first control current generation unit and a first mirror unit;

[0021] Figure 5 The circuit functional block diagram of an embodiment of the constant power control circuit when the second voltage-controlled current source control module in this application consists of a second control current generation unit and a second mirror unit;

[0022] Figure 6 The circuit functional block diagram of an embodiment of the constant power control circuit when the initial threshold setting module in this application consists of a voltage signal generation unit, a third mirror unit, a third resistor, and a fourth resistor;

[0023] Figure 7 The circuit structure schematic diagram of an embodiment of the constant power control circuit in this application;

[0024] Figure 8 The flowchart of an embodiment of the constant power control method in this application;

[0025] Figure 9 The circuit functional block diagram of the LED linear constant power system of an embodiment of the constant power control method in this application.

[0026] The realization, functional features, and advantages of the purpose of this application will be further described in conjunction with the embodiments with reference to the accompanying drawings.

[0027] Explanation of the reference numerals in the accompanying drawings:

[0028]

[0029] Specific implementation manners

[0030] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without making creative efforts belong to the scope protected by this application.

[0031] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the attached drawings). If the specific posture changes, the directional indications will change accordingly.

[0032] In addition, the descriptions involving "first", "second", etc. in this application are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by this application.

[0033] This application provides a constant power control circuit. In an embodiment of this application, the constant power control circuit includes a peak voltage sampling and holding module 10, a first voltage-controlled current source control module 20, a second voltage-controlled current source control module 30, an initial threshold setting module 40, and a constant current threshold control module 50.

[0034] Refer to Figure 1 , in this embodiment, the output end of the peak voltage sampling and holding module 10 is connected to the input ends of the first voltage-controlled current source control module 20 and the second voltage-controlled current source control module 30. The output end of the first voltage-controlled current source control module 20 is connected to the input end of the constant current threshold control module 50. The output end of the second voltage-controlled current source control module 30 is connected to the input end of the initial threshold setting module 40 and the input end of the constant current threshold control module 50.

[0035] After the peak voltage sampling and holding module 10 collects the voltage at the input end to generate a corresponding input voltage sampling signal, it outputs a corresponding output voltage signal to the first voltage-controlled current source control module 20 and the second voltage-controlled current source control module 30 according to the peak voltage of the input voltage sampling signal and the voltage value of the input voltage sampling signal at the previous time step. Wherein, the voltage value of the output voltage signal is the average voltage value of the input voltage sampling signal and the input voltage sampling signal of the time step; the first voltage-controlled current source control module 20 outputs a corresponding first current source signal to the constant current threshold control module 50 according to the output voltage signal and the first preset threshold voltage. Wherein, the first preset threshold voltage is the input voltage value when the luminous power of the LED lamp is constant and input to the constant power control circuit. The second voltage-controlled current source control module 30 outputs a corresponding second current source signal to the initial threshold setting module 40 and the constant current threshold control module 50 according to the output voltage signal and the first preset threshold voltage; the initial threshold setting module 40 outputs a corresponding first threshold voltage signal to the constant current threshold control module 50 according to the second current source signal and the second preset threshold voltage; wherein, the second preset threshold voltage is the voltage value input to the constant current threshold control module 50 when the luminous power of the LED lamp is constant, and the constant current threshold control module 50 adjusts the drain current output by the constant current threshold control module 50 according to the first current source signal, the second current source signal and the first threshold voltage signal to stabilize the luminous power of the LED lamp in the LED linear constant power system.

[0036] As an example, the peak voltage sampling and holding module 10 generates an input voltage signal by collecting the input voltage at the input end, and generates a corresponding reset signal according to the input voltage signal and the third preset threshold voltage. Then, based on the reset signal, it collects the peak voltage of the input voltage signal to obtain a first peak voltage signal; generates a corresponding single-machine signal according to the first peak voltage signal and the input voltage signal; performs voltage following on the first peak voltage signal to obtain a second peak voltage signal, wherein the second peak voltage signal has the same amplitude and phase as the first peak voltage signal; based on the single-machine signal, the voltage value of the second peak voltage signal is periodically obtained according to the level state of the single-machine signal to obtain an output voltage signal, wherein the level state includes a high level or a low level. The peak voltage sampling and holding module 10 can provide an output voltage signal with a stable waveform for the constant power control circuit by periodically obtaining the voltage value at the input end, that is, the output voltage signal will not have too large waveform changes due to the periodic change of the input voltage signal.

[0037] As an example, the first voltage-controlled current source control module 20 and the second voltage-controlled current source control module 30 generate corresponding first control current signal and second control current signal by comparing the voltage value of the output voltage signal with the magnitude of the first preset threshold voltage; if the voltage value of the output voltage signal is greater than the first preset threshold voltage, the second control current signal is zero, and if the voltage value of the output voltage signal is not greater than the first preset threshold voltage, the first control current signal is zero; amplify the first control current signal and the second control current signal to obtain a first current source signal and a second current source signal. When the input voltage is too high, the first voltage-controlled current source control module 20 provides the first current source signal to act on the constant power control circuit to reduce the drain current of the constant power control circuit, and when the input voltage is too low, the second voltage-controlled current source control module 20 provides the second current source signal to act on the constant power control circuit to increase the drain current of the constant power control circuit.

[0038] As an example, the initial threshold setting module 40 converts the second preset threshold voltage into a second threshold voltage signal through a threshold voltage signal generating unit, amplifies the second threshold voltage signal to obtain a third threshold voltage signal; superimposes the third threshold voltage signal and the second current source signal to obtain a first threshold voltage signal. The initial threshold setting module 40 provides the first threshold voltage for the constant power control circuit to ensure the conduction of the constant power control circuit.

[0039] As an example, when the second current source signal is zero, the constant current threshold control module 50 superimposes the first threshold voltage signal and the first current source signal through a modulation voltage signal generating unit to weaken the first threshold voltage signal and generate a corresponding modulation voltage signal, and reduces the drain current output by the constant current threshold control module 50 according to the voltage value of the modulation voltage signal; when the first current source signal is zero, the constant current threshold control module 50 superimposes the first threshold voltage signal and the second current source signal through a modulation voltage signal generating unit to enhance the first threshold voltage signal and generate a corresponding modulation voltage signal, and increases the drain current output by the constant current threshold control module 50 according to the voltage value of the modulation voltage signal. The constant current threshold control module 50 adjusts the drain current output by the constant power control circuit by generating a modulation voltage signal to achieve the purpose of stabilizing the LED luminous power.

[0040] As an example, refer to Figure 2, the constant current threshold control module 50 includes a first operational amplifier Y1, a first switching transistor M1, a first resistor R1, and a second resistor R2. The output terminal of the first operational amplifier Y1 is connected to the gate of the first switching transistor M1. The inverting input terminal of the first operational amplifier Y1 is connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 is grounded. The source of the first switching transistor M1 is connected to the first end of the second resistor R2. If it is detected that the voltage value of the output voltage signal V5 is greater than the first preset threshold voltage Vref1, then the second current source signal I_VT2 is zero. According to the first current source signal I_VT1 and the first threshold voltage signal Vref4, the gate current output by the first operational amplifier Y1 to the gate of the first switching transistor M1 is reduced, thereby reducing the drain current Idrain output by the constant current threshold control module. If it is detected that the voltage value of the output voltage signal V5 is not greater than the first preset threshold voltage Vref1, then the first current source signal I_VT1 is zero. According to the second current source signal I_VT2 and the first threshold voltage signal Vref4, the gate current output by the first operational amplifier Y1 to the gate of the first switching transistor M1 is increased, thereby increasing the drain current Idrain output by the constant current threshold control module. That is, when the voltage value of the output voltage signal V5 is greater than the first preset threshold voltage Vref1, the system power is reduced by reducing the drain current Idrain. When the voltage value of the output voltage signal V5 is not greater than the first preset threshold voltage Vref1, the system power is increased by increasing the drain current Idrain, so as to ensure that the input power of the system remains basically unchanged.

[0041] As an example, when the voltage value of the output voltage signal is greater than the first preset threshold voltage and the size ratio of the switching transistor and the resistance ratio of the resistor in the initial threshold setting module 40 are both 1, the drain current is calculated as follows:

[0042] Idrain = (V ref2 -(I_VT1*(R1 + R2))) / R2

[0043] where, Idrain is the drain current, V ref2 is the second preset threshold voltage, I_VT1 is the first current source signal, R1 is the resistance value of the first resistor, and R2 is the resistance value of the second resistor.

[0044] As an example, when the voltage value of the output voltage signal is not greater than the first preset threshold voltage and the size ratio of the switching transistor and the resistance ratio of the resistor in the initial threshold setting module 40 are both 1, the drain current is calculated as follows:

[0045] Idrain = V ref4 / R2 = (Vref2 +(I_VT2 * R4)) / R2

[0046] Wherein, Idrain is the drain current, V ref4 is the first threshold voltage signal, R2 is the resistance value of the second resistor, V ref2 is the second preset threshold voltage, I_VT2 is the second current source signal, and R4 is the resistance value of the fourth resistor.

[0047] As an example, referring to Figure 3, the peak voltage sampling and holding module 10 includes a line network voltage sampling unit 101, a reset signal generation unit 102, a line network voltage peak sampling unit 103, a single-machine signal generation unit 104, a voltage follower unit 105, and a voltage averaging unit 106. The output terminal of the line network voltage sampling unit 101 is connected to the input terminal of the reset signal generation unit 102, the input terminal of the line network voltage peak sampling unit 103, and the input terminal of the single-machine signal generation unit 104. The output terminal of the reset signal generation unit 102 is connected to the input terminal of the line network voltage peak sampling unit 103. The output terminal of the line network voltage peak sampling unit 103 is connected to the input terminal of the single-machine signal generation unit 104 and the input terminal of the voltage follower unit 105. The output terminal of the single-machine signal generation unit 104 is connected to the input terminal of the voltage averaging unit 106. The output terminal of the voltage follower unit 105 is connected to the input terminal of the voltage averaging unit. The output terminal of the voltage averaging unit is connected to the input terminals of the first voltage-controlled current source control module 20 and the second voltage-controlled current source control module 30. After the line network voltage sampling unit 101 samples the input voltage VIN at the input terminal and generates a corresponding input voltage sampling signal, the reset signal generation unit 102 will generate a corresponding reset signal RST according to the input voltage sampling signal and the third preset threshold voltage Vref3. Among them, the input voltage sampling signal includes a first input voltage signal V1 and a second input voltage signal V2. The line network voltage peak sampling unit 103 periodically samples the second input voltage signal V2 according to the reset signal RST and the second input voltage signal V2 to generate a corresponding first peak voltage signal V3. The single-machine signal generation unit 104 generates a corresponding single-machine signal CLK_A according to the first peak voltage signal V3 and the first input voltage signal V1. The voltage follower unit 105 generates a corresponding second peak voltage signal V4 according to the first peak voltage signal V3. Among them, the amplitudes and phases of the first peak voltage signal V3 and the second peak voltage signal V4 are the same. The voltage averaging unit 106 transfers the second peak voltage signal V4 when the single-machine signal CLK_A is at a high level to obtain a corresponding output voltage signal V5. By periodically obtaining the peak signal of the input voltage through the single-machine signal CLK_A, the voltage value of the output voltage signal V5 is kept stable, thereby maintaining the normal operation of the constant power control circuit.

[0048] As an example, refer to Figure 4, the first voltage-controlled current source control module 20 includes a first control current generation unit 201 and a first mirror unit 202. The output end of the first control current generation unit 201 is connected to the input end of the first mirror unit 202, and the output end of the first mirror unit 202 is connected to the inverting input end of the first operational amplifier Y1. The first control current generation unit 201 generates a first control current signal I_VT3 according to the output voltage signal V5 and the first preset threshold voltage Vref1. After the first mirror unit 202 amplifies the first control current signal I_VT3, a first current source signal I_VT1 is obtained. When the input voltage VIN is relatively large, this module generates a first power source control signal I_VT1 and inputs a reverse voltage to the output of the constant current threshold control module 50 to reduce the threshold current Idrain, thereby maintaining the constancy of the system input power. At the same time, by generating and amplifying the current source signal, it can prevent the situation where the constant power control circuit cannot operate normally due to too small current, thus ensuring the normal operation of the constant power control circuit.

[0049] As an example, refer to Figure 5 , the second voltage-controlled current source control module 30 includes a second control current generation unit 301 and a second mirror unit 302. The output end of the second control current generation unit 301 is connected to the input end of the second mirror unit 302, and the output end of the second mirror unit 302 is connected to the input end of the initial threshold setting module 40 and the non-inverting input end of the first operational amplifier Y1. The second control current generation unit 301 generates a second control current signal I_VT4 according to the output voltage signal V5 and the first preset threshold voltage Vref1. After the second mirror unit 302 amplifies the second control current signal I_VT4, a second current source signal I_VT2 is obtained. When the input voltage VIN is relatively small, this module generates a second current source signal I_VT2 to increase the non-inverting input voltage of the constant current threshold control module 50 to increase the threshold current Idrain, thereby maintaining the constancy of the system input power. At the same time, by generating and amplifying the current source signal, it can prevent the situation where the constant power control circuit cannot operate normally due to too small current, thus ensuring the normal operation of the constant power control circuit.

[0050] As an example, refer to Figure 6, the initial threshold setting module 40 includes a threshold voltage signal generating unit 401, a third mirror unit 402, a third resistor R3, and a fourth resistor R4. The output end of the threshold voltage signal generating unit 401 is connected to the input end of the third mirror unit 402. The output end of the third mirror unit 402 is connected to the first end of the third resistor R3 and the first end of the fourth resistor R4. The second end of the third resistor R3 is grounded. The first end of the fourth resistor R4 is connected to the output end of the second mirror unit 302. The second end of the fourth resistor R4 is connected to the non-inverting input end of the seventh operational amplifier. The threshold voltage signal generating unit 401 generates a corresponding second threshold voltage signal Vref5 according to the second preset threshold voltage Vref2. The second threshold voltage signal Vref5 is amplified by the third mirror unit 402 to obtain a third threshold voltage signal Vref6. A corresponding first threshold voltage signal Vref4 is generated according to the third threshold voltage signal Vref6 and the second current source signal I_VT2. When the voltage value of the output voltage signal V5 is greater than the first preset threshold voltage Vref1, the first threshold voltage signal Vref4 remains unchanged, so as to provide a stable non-inverting input voltage for the constant current threshold control module 50. When the voltage value of the output voltage signal V5 is not greater than the first preset threshold voltage Vref1, the first threshold voltage signal Vref4 will increase, thereby increasing the non-inverting input voltage. By controlling the voltage value of the first threshold voltage signal Vref4, the input power of the system can be ensured to remain basically unchanged.

[0051] As an example, refer to Figure 7 , the constant power control circuit is composed of a peak voltage sampling and holding module 10, a first voltage-controlled current source control module 20, a second voltage-controlled current source control module 30, an initial threshold setting module 40, and a constant current threshold control module 50.

[0052] Optionally, the line network voltage sampling unit 101 may include a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The reset signal generation unit 102 may include a second operational amplifier Y2 and an RST signal generator. The line network voltage peak sampling unit 103 may include a third operational amplifier Y3, a second switching transistor M2, a third switching transistor M3, a fourth switching transistor M4, and a first capacitor C1. The single machine signal generation unit 104 may include a fourth operational amplifier Y4 and a CLK_A signal generator. The voltage follower unit 105 may include a fifth operational amplifier Y5 and a second capacitor C2. The voltage averaging unit 106 may include a fifth switching transistor M5, an eighth resistor R8, and a third capacitor C3. Specifically, the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7. The second end of the seventh resistor R7 is grounded. The midpoint B1 between the fifth resistor R5 and the sixth resistor R6 is connected to the inverting input terminal of the fourth operational amplifier Y4. The midpoint B2 between the sixth resistor R6 and the seventh resistor R7 is connected to the non-inverting input terminal of the third operational amplifier Y3, the non-inverting input terminal of the second operational amplifier Y2, and the drain of the second switching transistor M2. The third preset threshold voltage Vref3 is connected to the inverting input terminal of the second operational amplifier Y2. The output terminal of the second operational amplifier Y2 is connected to the input terminal of the RST signal generator. The output terminal of the RST signal generator is connected to the gate of the fourth switching transistor M4 and the gate of the third switching transistor M3. The drain of the fourth switching transistor M4 is connected to the inverting input terminal of the third operational amplifier Y3 and the first end of the first capacitor C1. The source of the fourth switching transistor M4, the second end of the first capacitor C1, and the source of the third switching transistor M3 are grounded. The output terminal of the third operational amplifier Y3 is connected to the drain of the third switching transistor M3 and the gate of the second switching transistor M2. The source of the second switching transistor M2 is connected to the first end of the first capacitor C1, the non-inverting input terminal of the fourth operational amplifier Y4, and the non-inverting input terminal of the fifth operational amplifier Y5. The inverting input terminal of the fifth operational amplifier Y5 is connected to the first end of the second capacitor C2. The second end of the second capacitor is grounded. The output terminal of the fifth operational amplifier Y5 is connected to the first end of the second capacitor C2 and the drain of the fifth switching transistor M5. The output terminal of the fourth operational amplifier Y4 is connected to the input terminal of the CLK_A signal generator. The output terminal of the CLK_A signal generator is connected to the gate of the fifth switching transistor M5. The source of the fifth switching transistor M5 is connected to the first end of the eighth resistor R8. The second end of the eighth resistor R8 is connected to the first end of the third capacitor C3, the input terminal of the first voltage-controlled current source control module 20, and the input terminal of the second voltage-controlled current source control module 30. The second end of the third capacitor C3 is grounded.When the reset signal RST is at a high level, the second switching transistor M2 is turned off, the third switching transistor M3 and the fourth switching transistor M4 are turned on, the first capacitor C1 is in a discharging state, and the capacitor voltage drops to zero, thereby generating a first peak voltage signal V3; when the single machine signal CLK_A is at a high level, the fifth switching transistor M5 is turned on, and the second capacitor C2 and the third capacitor C3 perform charge transfer. After multiple cycles, the second peak voltage signal V4 is made equal to the output voltage signal V5. When the single machine signal CLK_A is at a low level, the fifth switching transistor M5 is turned off, thereby periodically obtaining the second peak voltage signal V4 to generate a corresponding output voltage signal V5.

[0053] Optionally, the first current control signal generating unit 201 may include a sixth operational amplifier Y6, a seventh operational amplifier Y7, a sixth switching transistor M6, and a ninth resistor R9. The first mirror unit 202 may include a seventh switching transistor M7 and an eighth switching transistor M8. Specifically, the output terminal of the sixth operational amplifier Y6 is connected to the gate of the sixth switching transistor M6. The first end of the ninth resistor R9 is connected to the inverting input terminal of the sixth operational amplifier Y6 and the source of the sixth switching transistor M6. The second end of the ninth resistor R9 is connected to the output terminal of the seventh operational amplifier Y7 and the inverting input terminal of the seventh operational amplifier Y7. The non-inverting input terminal of the seventh operational amplifier Y7 is connected to the first preset threshold voltage Vref1. The drain of the sixth switching transistor M6 is connected to the source and the gate of the seventh switching transistor M7. The gate of the seventh switching transistor M7 is connected to the gate of the eighth switching transistor M8. The drain of the seventh switching transistor M7 and the drain of the seventh switching transistor M7 are connected to the DC power supply VDD. The source of the eighth switching transistor M8 is connected to the inverting input terminal of the constant current threshold control module 50. According to the size ratio K1 of the eighth switching transistor M8 and the seventh switching transistor M7, the first control current signal I_VT3 can be amplified to obtain the first current source signal I_VT1.

[0054] As an example, the first current source signal is calculated as follows:

[0055] I_VT1 = K1 * I_VT3 = K1 * (V5 - V ref1 ) / R9

[0056] Where, I_VT1 is the first current source signal, K1 is the size ratio of the eighth switching transistor and the seventh switching transistor, I_VT3 is the first control current signal, V5 is the output voltage signal, V ref1 is the first preset threshold voltage, and R9 is the resistance value of the ninth resistor.

[0057] Optionally, the second current control signal generating unit 301 may include an eighth operational amplifier Y8, a ninth operational amplifier Y9, an eleventh switching transistor M11, and a tenth resistor R10. The second mirror unit 302 may include a ninth switching transistor M9 and a tenth switching transistor M10. Specifically, the non-inverting input terminal of the eighth operational amplifier Y8 is connected to the first preset threshold voltage Vref1. The output terminal of the eighth operational amplifier Y8 is connected to the gate of the eleventh switching transistor R11. The first end of the tenth resistor R10 is connected to the inverting input terminal of the eighth operational amplifier Y8 and the source of the eleventh switching transistor M11. The second end of the tenth resistor R10 is connected to the output terminal and the inverting input terminal of the ninth operational amplifier Y9. The drain of the eleventh switching transistor M11 is connected to the source and the gate of the ninth switching transistor M9. The gate of the ninth switching transistor M9 is connected to the gate of the tenth switching transistor M10. The drain of the ninth switching transistor M9 and the drain of the tenth switching M10 are connected to the DC power supply VDD. The source of the tenth switching transistor M10 is connected to the non-inverting input terminal of the constant current threshold control module 50 and the input terminal of the initial threshold setting module 40. According to the size ratio K2 of the tenth switching transistor M10 and the ninth switching transistor M9, the second control current signal I_VT4 can be amplified to obtain the second current source signal I_VT2.

[0058] As an example, the second current source signal is calculated as follows:

[0059] I_VT2 = K2 * I_VT4 = (V ref1 - V5) / R 10

[0060] where I_VT2 is the second current source signal, K2 is the size ratio of the tenth switching transistor and the ninth switching transistor, I_VT4 is the second control current signal, V ref1 is the first preset threshold voltage, V5 is the output voltage signal, and R 10 is the resistance value of the tenth resistor.

[0061] Optionally, the threshold voltage signal generating unit 401 may include a tenth operational amplifier Y10, a twelfth switching transistor M12, and an eleventh resistor R11. The third mirror unit 402 may include a thirteenth switching transistor M13 and a fourteenth switching transistor M14. Specifically, the non-inverting input terminal of the tenth operational amplifier Y10 is connected to the second preset threshold voltage. The output terminal of the tenth operational amplifier is connected to the gate of the twelfth switching transistor M12. The first terminal of the eleventh resistor R11 is connected to the inverting input terminal of the tenth operational amplifier Y10 and the source of the twelfth switching transistor M12. The second terminal of the eleventh resistor R11 is grounded. The drain of the twelfth switching transistor M12 is connected to the source and the gate of the thirteenth switching transistor M13. The gate of the thirteenth switching transistor M13 is connected to the gate of the fourteenth switching transistor M14. The drain of the thirteenth switching transistor M13 and the drain of the fourteenth switching transistor M14 are connected to the DC power supply VDD. The source of the fourteenth switching transistor M14 is connected to the first terminal of the tenth resistor R10 and the first terminal of the eleventh resistor R11. The second terminal of the tenth resistor R10 is grounded. The second terminal of the eleventh resistor R11 is connected to the output terminal of the second voltage-controlled current source control module 30 and the non-inverting input terminal of the constant current threshold control module 50. According to the size ratio K3 of the fourteenth switching transistor M14 and the thirteenth switching transistor M13 and the resistance ratio K4 of the third resistor R3 and the eleventh resistor R11, the second threshold voltage signal Vref5 can be amplified or reduced to obtain a third threshold voltage signal Vref6.

[0062] In the embodiment of the present application, a constant power control circuit is composed of a peak voltage sampling and holding module, a first voltage-controlled current source control module, a second voltage-controlled current source control module, an initial threshold setting module, and a constant current threshold control module. In this constant power control circuit, the peak voltage sampling and holding module is used to collect the voltage at the input end to generate a corresponding input voltage sampling signal, and according to the peak voltage of the input voltage sampling signal and the voltage value of the input voltage sampling signal at the previous time step, an output voltage signal is output to the first voltage-controlled current source control module and the second voltage-controlled current source control module; the first voltage-controlled current source control module is used to output a corresponding first current source signal to the constant current threshold control module according to a first preset threshold voltage and the output voltage signal; the second voltage-controlled current source control module is used to output a corresponding second current source signal to the constant current threshold control module and the initial threshold setting module according to the first preset threshold voltage and the output voltage signal; the initial threshold setting module is used to output a corresponding first threshold voltage signal to the constant current threshold control module according to the second current source signal and a second preset threshold voltage; the constant current threshold control module is used to adjust the drain current output by the constant current threshold control module according to the first current source signal, the second current source signal, and the first threshold voltage signal, so as to stabilize the light-emitting power of the LED in the LED linear constant power system. The embodiment of the present application can adjust the drain current output by the system according to the magnitude of the input voltage. When the input voltage is large, the output drain current is reduced. When the input voltage is small, the output drain current is increased, which can avoid the situation that the output power of the entire driving device changes due to the change of the system input voltage while the drain current remains unchanged, thereby stabilizing the light-emitting power of the LED lamp.

[0063] The present application also provides a constant power control circuit method, which is applied to the above constant power control circuit, referring to Figure 8 , and in combination with Figures 1 to 7 , the constant power control method includes:

[0064] Step S10, if it is detected that an output voltage signal is generated, then a corresponding first current source signal and a second current source signal are generated according to the output voltage signal and a first preset threshold voltage;

[0065] As an example, step S10 includes: collecting the input voltage VIN at the input end and generating a corresponding input voltage signal according to the input voltage VIN; generating a corresponding reset signal RST according to the input voltage signal and the third preset threshold voltage VRef3; based on the reset signal RST, collecting the peak signal of the input voltage signal to obtain the first peak voltage signal V3; generating a corresponding single-machine signal CLK_A according to the first peak voltage signal V3 and the input voltage signal; performing voltage following on the first peak voltage signal V3 to obtain a second peak voltage signal V4, where the second peak voltage signal V4 has the same amplitude and phase as the first peak voltage signal V3; based on the single-machine signal CLK_A, periodically obtaining the voltage value of the second peak voltage signal V4 according to the level state of the single-machine signal to obtain an output voltage signal V5, where the level state includes a high level or a low level. Generating a corresponding first current source signal I_VT1 and a second current source signal I_VT2 according to the output voltage signal V5 and the first preset threshold voltage Vref1, where the first preset threshold voltage Vref1 is the input voltage value input to the constant power control circuit when the luminous power of the LED lamp is constant. If the voltage value of the output voltage signal V5 is greater than the first preset threshold voltage Vref1, then the generated second current source signal I_VT2 is zero; if the voltage value of the output voltage signal V5 is not greater than the first preset threshold voltage Vref1, then the first current source signal I_VT1 is zero.

[0066] Step S20, generating a corresponding first threshold voltage signal according to the second current source signal and the second preset threshold voltage;

[0067] As an example, step S20 includes: performing voltage signal conversion on the second preset threshold voltage Vref2 to obtain a second threshold voltage signal; amplifying the second threshold voltage signal to obtain a third threshold voltage signal; superimposing the second current source signal I_VT2 and the second threshold voltage signal to enhance the second threshold voltage signal to obtain the first threshold voltage signal Vref4.

[0068] Step S30, adjusting the drain current output by the constant power control circuit according to the first current source signal, the second current source signal, and the first threshold voltage signal to stabilize the luminous power of the LED lamp in the LED linear constant power system.

[0069] As an example, step S30 includes: when the second current source signal I_VT2 is zero, superimposing the first threshold voltage signal Vref4 and the first current source signal I_VT1 to weaken the first threshold voltage Vref4 signal and generate a corresponding modulation voltage signal, and reducing the drain current Idrain output by the constant power control circuit according to the voltage value of the modulation voltage signal; when the first current source signal I_VT1 is zero, superimposing the first threshold voltage signal Vref4 and the second current source signal I_VT2 to enhance the first threshold voltage signal Vref4 and generate a corresponding modulation voltage signal, and increasing the drain current Idrain output by the constant power control circuit according to the voltage value of the modulation voltage signal, so as to stabilize the light emission power of the LED lamp in the LED linear constant power system.

[0070] Wherein, the step of generating the corresponding first current source signal and second current source signal according to the output voltage signal and the first preset threshold voltage includes:

[0071] Step S11, generating corresponding first control current signal and second control current signal according to the output voltage signal and the first preset threshold voltage;

[0072] Step S12, amplifying the first control current signal and the second control current signal to obtain the first current source signal and the second current source signal.

[0073] As an example, steps S11 to S12 include: generating corresponding first control current signal I_VT3 and second control current signal I_VT4 by comparing the voltage value of the output voltage signal V5 and the first preset threshold voltage Vref1; if the voltage value of the output voltage signal V5 is greater than the first preset threshold voltage Vref1, the second control current signal I_VT4 is zero, and if the voltage value of the output voltage signal V5 is not greater than the first preset threshold voltage Vref1, the first control current signal I_VT3 is zero; amplifying the first control current signal and the second control current signal I_VT4 to obtain the first current source signal I_VT1 and the second current source signal I_VT2.

[0074] It can be understood that since the above constant power control circuit is used in the constant power control method, therefore, the embodiments of the constant power control method include all the technical solutions of all the embodiments of the above constant power control circuit, and the achieved technical effects are also exactly the same, which will not be elaborated here.

[0075] In addition, the present application also provides an LED linear constant power system, referring to Figure 9, the LED linear constant power system includes a rectifier circuit 1001, an LED load 1002, and the above-mentioned constant power control circuit. The output end of the rectifier circuit 1001 is connected to the input end of the peak voltage sampling and holding module 10 and the input end of the LED load 1002. The output end of the LED load 1002 is connected to the output end of the constant current threshold control module 50. It can be understood that since the above-mentioned constant power control circuit is used in the LED linear constant power system, therefore, the embodiments of this LED linear constant power system include all the technical solutions of all the embodiments of the above-mentioned constant power control circuit, and the achieved technical effects are also exactly the same, which will not be elaborated here.

[0076] The foregoing is only a preferred embodiment of the present application, and thus does not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the specification and drawings of the present application under the application concept of the present application, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A constant power control circuit, characterized in that, The constant power control circuit includes: A peak voltage sampling and holding module, which is used to collect the voltage at the input end to generate a corresponding input voltage sampling signal, and output a corresponding output voltage signal to the first voltage-controlled current source control module and the second voltage-controlled current source control module according to the peak voltage of the input voltage sampling signal and the voltage value of the input voltage sampling signal at the previous time step; The first voltage-controlled current source control module, which is used to output a corresponding first current source signal to the constant current threshold control module according to the first preset threshold voltage and the output voltage signal; The second voltage-controlled current source control module, which is used to output a corresponding second current source signal to the constant current threshold control module and the initial threshold setting module according to the first preset threshold voltage and the output voltage signal; The initial threshold setting module, which is used to output a corresponding first threshold voltage signal to the constant current threshold control module according to the second current source signal and the second preset threshold voltage; The constant current threshold control module, which is used to adjust the drain current output by the constant current threshold control module according to the first current source signal, the second current source signal and the first threshold voltage signal, so as to stabilize the luminous power of the LED in the LED linear constant power system.

2. The constant power control circuit according to claim 1, wherein The constant current threshold control module includes: A first operational amplifier, which is used to adjust the non-inverting input voltage of the first operational amplifier according to the first current source signal, the second current source signal and the first threshold voltage signal, and output a corresponding gate current to the gate of the first switching tube; The first switching tube, which is used to output the drain current at the drain of the first switching tube according to the gate current, and output a corresponding source current to the second end of the first resistor and the first end of the second resistor according to the drain current and the gate current; The first resistor and the second resistor are used to set the drain output current of the first switching tube. The first end of the first resistor is connected to the inverting input terminal of the first operational amplifier, and the second end of the second resistor is grounded.

3. The constant power control circuit according to claim 2, wherein If it is detected that the first current source signal is zero, the non-inverting input voltage is increased according to the second current source signal and the first threshold voltage signal to increase the drain current output by the constant current threshold control module; if it is detected that the second current source signal is zero, the voltage across the first resistor is increased according to the first current source signal and the first threshold voltage signal to reduce the drain current output by the constant current threshold control module.

4. The constant power control circuit according to claim 1, wherein The peak voltage sampling and holding module includes: A line voltage sampling unit, which is used to collect the voltage at the input end to generate a corresponding input voltage sampling signal, and output the input voltage sampling signal to the reset signal generation unit, the line voltage peak sampling unit and the single machine signal generation unit; The reset signal generation unit, which is used to output a corresponding reset signal to the line voltage peak sampling unit according to the input voltage sampling signal and the third preset threshold voltage; The line voltage peak sampling unit, which is used to output a corresponding first peak voltage signal to the single machine signal generation unit and the voltage follower unit according to the input voltage sampling signal and the reset signal; A single - machine signal generation unit, configured to output a corresponding single - machine signal to a voltage averaging unit according to the first peak voltage signal and the input voltage sampling signal; A voltage follower unit, configured to output a corresponding second peak voltage signal to the voltage averaging unit according to the first peak voltage signal; A voltage averaging unit, configured to generate a corresponding output voltage signal according to the second peak voltage signal and the single - machine signal.

5. The constant power control circuit according to claim 1, wherein The first voltage - controlled current source control module includes: A first control current generation unit, configured to output a corresponding first control current signal to a first mirror unit according to the output voltage signal and the first preset threshold voltage; A first mirror unit, configured to amplify the first control current signal to generate a corresponding first current source signal.

6. The constant power control circuit according to claim 1, wherein The second voltage - controlled current source control module includes: A second control current generation unit, configured to output a corresponding second control current signal to a second mirror unit according to the output voltage signal and the first preset threshold voltage; A second mirror unit, configured to amplify the second control current signal to generate a corresponding second current source signal.

7. The constant power control circuit according to claim 5 or 6, characterized in that If the voltage value of the output voltage signal is greater than the first preset threshold voltage, the second control current signal output by the second control current generation unit is zero; if the voltage value of the output voltage signal is not greater than the first preset threshold voltage, the first control current signal output by the first control current generation unit is zero.

8. The constant power control circuit according to claim 1, wherein, The initial threshold setting module includes: A threshold voltage signal generation unit, configured to output a corresponding second threshold voltage signal to a third mirror unit according to a second preset threshold voltage; A third mirror unit, configured to amplify the second threshold voltage signal to output a corresponding third threshold voltage signal to the first end of a third resistor and the first end of a fourth resistor; A third resistor, the second end of the third resistor is grounded; A fourth resistor, configured to generate the corresponding first threshold voltage signal according to the third threshold voltage signal and the second current source signal.

9. A constant power control method, characterized in that, Applied to the constant - power control circuit according to any one of claims 1 - 8, the constant - power control method includes: If it is detected that the output voltage signal is generated, generate a corresponding first current source signal and a second current source signal according to the output voltage signal and the first preset threshold voltage; Generate a corresponding first threshold voltage signal according to the second current source signal and the second preset threshold voltage; Adjust the drain current output by the constant - power control circuit according to the first current source signal, the second current source signal and the first threshold voltage signal to stabilize the light - emitting power of the LED in the LED linear constant - power system.

10. An LED linear constant power system, characterized in that, The LED linear constant - power system includes a rectifying circuit, an LED load and the constant - power control circuit according to any one of claims 1 - 8.

Images