WO2022116707A1 - 一种led恒功率电路及装置 - Google Patents

一种led恒功率电路及装置 Download PDF

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Publication number
WO2022116707A1
WO2022116707A1 PCT/CN2021/123922 CN2021123922W WO2022116707A1 WO 2022116707 A1 WO2022116707 A1 WO 2022116707A1 CN 2021123922 W CN2021123922 W CN 2021123922W WO 2022116707 A1 WO2022116707 A1 WO 2022116707A1
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Prior art keywords
led
led light
constant current
mos transistor
resistor
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PCT/CN2021/123922
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English (en)
French (fr)
Inventor
邓迅升
叶羽安
王前前
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深圳市晟碟半导体有限公司
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Publication of WO2022116707A1 publication Critical patent/WO2022116707A1/zh

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current

Definitions

  • the utility model relates to the technical field of LEDs, in particular to an LED constant power circuit and a device.
  • the purpose of the present invention is to provide an LED constant power circuit and device, which can keep the power relatively constant when the input voltage changes.
  • An LED constant power circuit includes a constant current module, N LED light strings connected in series in sequence, and N-1 sampling adjustment modules, where N is a positive integer greater than 1; wherein, the N-1 sampling adjustment modules are also respectively connected with The negative poles of the N-1 LED light strings are connected correspondingly, the negative pole of the Nth LED light string is connected to the constant current module, and the constant current module is also connected to the N-1th sampling adjustment module; the sampling adjustment module is used to control the lighting of the LED light string and control the current flowing through the corresponding LED light string, so that the number of LED light strings lit is positively correlated with the value of the line voltage, and the current value is negatively correlated with the number of LED light strings lit; the constant current module is used in the When the N LED light strings are all lit, the current flowing through the N LED light strings is controlled; the current value when the N LED light strings are all lit is smaller than any one or more points in the preceding N-1 LED light strings Current value when it is on.
  • each sampling adjustment module includes a constant current unit and a sampling unit; the constant current unit in each sampling adjustment module is respectively connected with the sampling unit and the negative pole of the corresponding LED light string; the first to the Nth The sampling units in the -2 sampling adjustment modules are correspondingly connected with the constant current unit in the next level sampling adjustment module; the sampling unit in the N-1th sampling adjustment module is connected with the constant current module.
  • each constant current unit includes a first operational amplifier, a first resistor, a second resistor and a first MOS tube; the non-inverting input terminal of the first operational amplifier is connected to the first reference voltage input terminal, and the first operational amplifier is connected to the first reference voltage input terminal.
  • the inverting input end of an operational amplifier is connected to one end of the first resistor and the sampling unit, the other end of the first resistor is connected to the source of the first MOS transistor and one end of the second resistor, the other end of the second resistor is grounded, and the first operation
  • the output end of the amplifier is connected to the gate of the first MOS tube, and the drain of the first MOS tube is connected to the negative pole of the corresponding LED light string.
  • each sampling unit includes a second operational amplifier, a second MOS tube, a third resistor, a third MOS tube and a fourth MOS tube; the non-inverting input end of the second operational amplifier is connected to the constant current module Or the next-stage constant current unit, the inverting input end of the second operational amplifier is connected to one end of the third resistor and the source of the second MOS tube, the other end of the third resistor is grounded, and the drain of the second MOS tube is connected to the third The drain of the MOS tube, the gate of the fourth MOS tube and the gate of the third MOS tube, the output end of the second operational amplifier is connected to the gate of the second MOS tube, the source of the third MOS tube and the fourth MOS tube
  • the sources of the MOS transistors are all connected to the second reference voltage input terminal, and the drain electrodes of the fourth MOS transistors are connected to the constant current unit.
  • the constant current module includes a third operational amplifier, a fifth MOS tube, a fourth resistor and a fifth resistor; the non-inverting input terminal of the third operational amplifier is connected to the third reference voltage input terminal , the inverting input end of the third operational amplifier is connected to the N-1th sampling adjustment module and one end of the fourth resistor, and the other end of the fourth resistor is connected to the source of the fifth MOS transistor and one end of the fifth resistor , the other end of the fifth resistor is grounded, and the drain of the fifth MOS tube is connected to the negative electrode of the Nth LED light string
  • the first MOS transistor is an N-channel MOS transistor.
  • the second MOS transistor is an N-channel MOS transistor
  • the third MOS transistor and the fourth MOS transistor are both P-channel MOS transistors.
  • An LED constant power device includes a casing, a PCB board is arranged in the casing, and the above-mentioned LED constant power circuit is arranged on the PCB board.
  • the present invention provides an LED constant power circuit and device, wherein the LED constant power circuit includes a constant current module, N LED light strings connected in series in sequence, and N-1 LED light strings connected in series in sequence.
  • Sampling adjustment module, N is a positive integer greater than 1; wherein, N-1 sampling adjustment modules are also connected to the negative poles of N-1 LED light strings respectively, and the negative pole of the Nth LED light string is connected to the constant current module, constant current module.
  • the flow module is also connected to the N-1th sampling adjustment module; the utility model can effectively realize that the power of the LED lamp is relatively constant when the line voltage changes in a large range, and the luminous intensity of the LED lamp string remains unchanged.
  • 1a and 1b are circuit schematic diagrams and waveform diagrams of voltage signals and current signals of an existing LED control circuit
  • FIG. 2 is a structural block diagram of an LED constant power circuit provided by the utility model
  • FIG. 3 is a circuit schematic diagram of the LED constant power circuit provided by the utility model.
  • the LED constant power circuit and device provided by the utility model can keep the power relatively constant when the input voltage changes.
  • An LED constant power circuit includes a rectifier module 100, a constant current module 200, N LED light strings connected in series in sequence, and N-1 LED light strings connected in series in sequence.
  • N is a positive integer greater than 1; wherein, the N-1 sampling adjustment modules 300 are also respectively connected to the negative poles of the N-1 LED light strings, and the negative pole of the Nth LED light string is connected to the constant current module.
  • the constant current module 200 is also connected to the N-1th sampling adjustment module 300; as shown in FIG. 2, each LED light string is LED1, LED2, ... LEDN, and each LED light string is connected in series, wherein the input end of LED1
  • the rectification module 100 is connected, and the output terminals of the first N-1 LED light strings are all connected to the N-1 sampling adjustment modules 300 correspondingly.
  • the first sampling adjustment module 300 when the line voltage Vin+>Vled1, the first sampling adjustment module 300 will be turned on, and the LED1 has a current Iled1 flowing to light up, wherein the current Iled1 is set by the first sampling adjustment module 300; when the line voltage Vin+> When Vled1+Vled2, the first sampling adjustment module 300 will be disconnected, and the second sampling adjustment module 300 will be turned on. After LED1 and LED2 are connected in series, a current ILed2 flows, and Iled2 is set by the second sampling adjustment module 300; and so on.
  • the line voltage Vin+>Vled1+Vled2+...+VledN-1 when the line voltage Vin+>Vled1+Vled2+...+VledN-1, the first sampling adjustment module 300 to the N-2 sampling adjustment module 300 are disconnected, the N-1 sampling adjustment module 300 is turned on, LED1, After LED 2...
  • a current IledN-1 flows, and IledN-1 is set by the N-1th sampling adjustment module 300; when the line voltage Vin+>Vled1+Vled2+...+VledN, the first sampling The adjustment module 300 to the N-1 th sampling adjustment module 300 is disconnected, the constant current module 200 is turned on, and the current IledN flows after LED1, LED2...
  • IledN is set by the constant current module 200; wherein, Vled1 , Vled2...VledN corresponds to the voltage of each LED string, Iled1, Iled2...IledN-1 corresponds to the current set by each sampling adjustment module 300, IledN corresponds to the current set by the constant current module 200, and Iled1>Iled2...>IledN-1>IledN;
  • the power of the LED lamp is relatively constant when the line voltage changes in a large range, the luminous intensity of the LED light string is basically unchanged, and the LED light string is divided into multiple sections, which can be lit when the input line voltage is low, making the LED light
  • the light string has a longer lighting time and a wider range of line voltages.
  • each sampling adjustment module 300 includes a constant current unit 310 and a sampling unit 320, that is to say, N-1 sampling adjustment modules 300 respectively have N-1 constant current units 310 and N corresponding to the constant current units 310.
  • -1 sampling unit 320; the constant current unit 310 in each sampling adjustment module 300 is respectively connected with the sampling unit 320 and the negative pole of the corresponding LED light string; the sampling units 320 in the first to N-2th sampling adjustment modules 300 Correspondingly, it is connected to the constant current unit 310 in the next-level sampling adjustment module 300; the sampling unit 320 in the N-1 th sampling adjustment module 300 is connected to the constant current module 200; that is, in the first sampling adjustment module 300 The sampling unit 320 is connected with the constant current unit 310 in the second sampling adjustment module 300, the sampling unit 320 in the second sampling adjustment module 300 is connected with the constant current unit 310 in the third sampling adjustment module 300, and so on , the sampling unit 320 in the N-2 sampling adjustment module 300 is connected to the constant current unit 310 in the N-1 sampling adjustment
  • Each constant current unit 310 is configured to be turned on or off according to the control signal output by the sampling unit 320 , so as to control the turn on or off of the current of the LED light string connected to the constant current unit 310 , so as to realize the control of the LED light string.
  • Adjustment of the number of lights specifically, when the voltage value of the control signal received by the constant current unit 310 is greater than the first reference voltage, the constant current unit 310 is disconnected, and when the voltage value of the control signal received by the constant current unit 310 is less than the first reference voltage
  • the constant current unit 310 is turned on; and among the N-1 sampling units 320 connected in series, the sampling unit 320 of the upper level samples the control signal output by the sampling unit 320 of the next level, and according to the sampling result to output a control signal to control the on or off of the constant current unit 310 of the current stage, wherein the N ⁇ 1 th sampling unit 320 controls the N ⁇ 1 th constant current unit 310 according to the input voltage of the constant current module 200
  • the sampling unit 320 On or off, specifically, when the voltage value obtained by the sampling unit 320 sampling the control signal output by the next-stage sampling unit 320 is greater than the preset voltage, the corresponding output control signal is greater than the first voltage reference voltage, when the sampling unit 320:
  • the first constant current unit 310 when the line voltage Vin+>Vled1, the first constant current unit 310 will be turned on, and the LED1 will be lit with the current Iled1 flowing, wherein the current Iled1 is set by the first constant current unit 310; when the line voltage Vin+>Vled1+ At Vled2, the first constant current unit 310 will be turned off, the second constant current unit 310 will be turned on, and the current ILed2 flows after LED1 and LED2 are connected in series, and Iled2 is set by the second constant current unit 310; and so on, when the line voltage When Vin+>Vled1+Vled2+...+VledN-1, the first constant current unit 310 to the N-2th constant current unit 310 are turned off, the N-1th constant current unit 310 is turned on, LED1, LED2...and LED After N-1 is connected in series, a current IledN-1 flows, and IledN-1 is set by the N-1th constant current unit 310; when the line voltage Vin+>Vled1+Vled2+...
  • the number of LED light strings lit is larger, and the current flowing through the LED light string is smaller.
  • the line voltage decreases the number of LED light strings lit is smaller, and the current flowing through the LED light string is larger.
  • three LED light strings connected in series are used as an example to describe the working principle of the LED constant power circuit.
  • the number of light strings connected in series can be set as required. This is not limited; then two constant current units 310 and sampling units 320 are correspondingly provided, and the sampling unit 320 is respectively denoted as sampling unit 1 and sampling unit 2, constant current unit 310 is constant current unit 1 and constant current unit 2, LED
  • the light strings are LED1, LED2 and LED3.
  • Vled1, Vled2 and Vled3 are the voltage of LED 1, LED 2 and LED 3 respectively
  • Iled1, Iled2 and Iled3 are the constant current set by constant current unit 1, the constant current and constant current set by constant current unit 2 respectively The constant current set by the flow module 200.
  • Iled1 is the current flowing from LED 1 to Vin- through constant current unit 1
  • Iled2 is the current flowing to Vin- through constant current unit 2 after LED 1 and LED 2 are connected in series
  • Iled3 is LED 1, LED2 and LED 3 The current flowing to Vin- through the constant current module 200 after being connected in series.
  • each constant current unit 310 includes a first voltage source, a first operational amplifier, a first resistor, a second resistor and a first MOS transistor; the non-inverting input terminal of the first operational amplifier is connected to the positive pole of the first voltage source, and the first The negative pole of a voltage source is grounded, the inverting input terminal of the first operational amplifier is connected to one end of the first resistor and the sampling unit, the other end of the first resistor is connected to the source of the first MOS transistor and one end of the second resistor, and the second resistor The other end of the first operational amplifier is grounded, the output end of the first operational amplifier is connected to the gate of the first MOS tube, and the drain of the first MOS tube is connected to the negative pole of the corresponding LED light string.
  • the first MOS tube is an N-channel MOS tube ; wherein, the first voltage source is used to provide a first reference voltage for the non-inverting input terminal of the first operational amplifier, and the inverting input terminal of the first operational amplifier is used to receive the control signal output by the corresponding sampling unit, and control the first MOS tube Specifically, when the first operational amplifier compares that the voltage value of the control signal is greater than the first reference voltage, the first MOS tube is controlled to be turned off, and the current flowing through the corresponding LED light string is turned off , otherwise, the first MOS transistor is controlled to be turned on, and a corresponding current flows through the corresponding LED light string.
  • the first operational amplifiers in the two constant current units 310 are respectively OP1a and OP2a
  • the first MOS transistors are N1a and N2a respectively
  • the first resistances are R1a and R2a respectively
  • the second resistances are Rcs1 and Rcs2 respectively
  • the first voltage sources are VR1a and VR2a respectively
  • the corresponding first reference voltages are VREF1 and VREF2 respectively
  • the control signals received by the two constant current units 310 are Ctrl1 and Ctrl2 respectively.
  • the control signal Ctrl1 from the sampling unit controls the turn-on or turn-off of N1a, and then controls the turn-on or turn-off of the current of LED 1; that is, when the voltage value of Ctrl1 is greater than VREF1, the OP1a output signal turns off N1a and flows through LED 1
  • the current of the LED is turned off, otherwise, N1a is turned on, and the LED 1 has the Iled1 current flowing through; the principle of the constant current unit 2 is the same as that of the constant current unit 1, and will not be repeated here.
  • each sampling unit 320 includes a second voltage source, a second operational amplifier, a second MOS transistor, a third resistor, a third MOS transistor and a fourth MOS transistor; the non-inverting input end of the second operational amplifier is connected to a constant current Module 200 or the next-stage constant current unit, the inverting input end of the second operational amplifier is connected to one end of the third resistor and the source of the second MOS transistor, the other end of the third resistor is grounded, and the drain of the second MOS transistor is connected The drain of the third MOS tube, the gate of the fourth MOS tube and the gate of the third MOS tube, the output end of the second operational amplifier is connected to the gate of the second MOS tube, the source of the third MOS tube and the fourth MOS tube.
  • the source of the MOS tube is connected to the positive pole of the second voltage source, the negative pole of the second voltage source is grounded, and the drain of the fourth MOS tube is connected to the constant current unit;
  • the second MOS tube is an N-channel MOS
  • the second operational amplifiers in the two sampling units 320 are respectively OP1b and OP2b, the second MOS transistors are N1b and N2b, the third MOS transistors are P2 and P4 respectively, and the fourth MOS transistors are P1 and P4 respectively.
  • P3 the third resistors are R1b and R2b respectively, the second voltage source is VR1b and VR2b respectively, and the second voltage source is used to provide the second reference voltage VREF.
  • the non-inverting input terminal of OP1b is connected to the inverting input terminal of OP2a.
  • Vin+ voltage is greater than Vled1+Vled2
  • the inverting input terminal voltage of OP2a in the constant current unit 2 rises to VREF2 with the Vin+ voltage.
  • the voltage of the non-inverting input terminal of OP1b is greater than or equal to the voltage of the inverting input terminal, and the output signal of OP1b makes N1b turn on, wherein the voltage of the inverting input terminal of OP1b corresponds to the preset voltage, and the voltage value of the preset voltage can be set by setting the first The resistance of the three resistors is adjusted.
  • the current Ip1 is jointly determined by the P1 tube, the P2 tube, the N1b tube, the resistors R1b, OP1b and Ctrl2.
  • the utility model reasonably selects the values of Ip1, R1a and Rcs1, so that when there is current Ip1, Ctrl1>VREF1, that is, the voltage of the inverting input terminal of OP1a is greater than the voltage of the non-inverting input terminal, the constant current unit 1 is disconnected, and the LED1 is not Current flows to Vin- through constant current unit 1. That is, the sampling unit 1 generates Ctrl1 for controlling the constant current unit 1 through the inverting input terminal voltage Ctrl2 of the OP2a in the constant current unit 2, thereby controlling the current of the constant current unit 1 to be turned off or turned on.
  • the sampling unit 2 will generate Ctrl2 that controls the constant current unit 2 through the input voltage Ctrl3 of the constant current module 200, thereby controlling the current of the constant current unit 2 to be turned off or turned on .
  • the constant current module 200 includes a third voltage source, a third operational amplifier, a fifth MOS transistor, a fourth resistor and a fifth resistor; the non-inverting input end of the third operational amplifier is connected to the positive electrode of the third voltage source, and the third The negative pole of the three voltage sources is grounded, the inverting input terminal of the third operational amplifier is connected to the N-1th sampling adjustment module and one end of the fourth resistor, and the other end of the fourth resistor is connected to the source of the fifth MOS tube and the fifth resistor One end of the fifth resistor is grounded, the drain of the fifth MOS tube is connected to the negative pole of the Nth LED light string, and the fifth MOS tube is an N-channel MOS tube.
  • the third voltage source is VR3a
  • the third operational amplifier is OP3a
  • the fifth MOS transistor is N3a
  • the fourth resistor is R3a
  • the fifth resistor is Rcs3; among them, the non-inverting input terminal of OP2b in the sampling unit 2 Connect the inverting input terminal of OP3a, then the sampling unit 2 will generate Ctrl2 that controls the constant current unit 2 through the input voltage Ctrl3 of the inverting input terminal of the third operational amplifier, thereby controlling the current of the constant current unit 2 to be disconnected or turned on;
  • the current is reduced in the same proportion or by a fixed value, which can maintain the power constant or make the variation range smaller, so that the driver chip can withstand less power to protect the driver chip from being damaged. damage.
  • Vin+>Vled1 use a larger current Iled1 to light up LED 1
  • Vin+ rises use a smaller current Iled2 to light up LED1 and LED2
  • Vin+ continues to rise use a smaller current Iled3 lights up LED1, LED2 and LED3.
  • the power variation range is smaller. If a smaller power variation is desired, the number of LED light strings can be increased in the present invention, and the voltage of each LED light string can be controlled according to the voltage value of Vin+. current to achieve.
  • the non-inverting input terminals of the LEDs are connected together to share a reference voltage VREF0.
  • Rcs1, Rcs2 and Rcs3 share a constant current resistor Rcs, that is, the inverting input terminals of the operational amplifiers OP1a, OP2a and OP3a are connected together to share a constant current resistor Rcs to ground, according to the light string
  • the current Iled VREF/Rcs, at this time, by setting VREF1>VREF2>VREF3, the effect of Iled1>Iled2>Iled3 can also be obtained.
  • the LED constant power circuit further includes an energy storage module 400.
  • the energy storage module 400 is used to store electric energy when the line voltage is greater than the charging voltage of the energy storage module 400, and release the electric energy when the line voltage is lower than the charging voltage of the energy storage module 400.
  • the energy storage module 400 can effectively eliminate the flicker of the LED light string.
  • the energy storage module 400 includes a capacitor C1, one end of the capacitor C1 is connected to the line voltage input terminal, and the other end of the capacitor C1 is grounded; the present invention can select a suitable capacitor C1 according to the working current of the LED light string by setting the energy storage module 400 When the voltage value of the line voltage Vin+ decreases, the capacitor C1 discharges the LED light string until the line voltage Vin+ is greater than the voltage of the capacitor C1 again, so as to ensure that the LED light string does not emit light with the line voltage Vin+. That is, no stroboscopic or stroboscopic depth is relatively low.
  • the utility model can also expand the working voltage range of the LED light strings to emit light.
  • the effect of expanding the working voltage range of the LED light strings in the present invention will be described in detail by taking the arrangement of three strings of LED light strings as an example.
  • Vled0 is 240V when one string is used
  • Vled1 is 160V when three strings are used
  • Vled2 is 40V
  • Vled2 is 40V
  • Vled1, Vled2 and Vled3 can also be other values, as long as the sum of the three is satisfied less than Vin+
  • Vin+ of 220V AC power rectified by the rectifier module is a voltage that changes periodically between 0V and 311V.
  • the lighting range is between 240V and 311V by the method of one string, and the lighting by the method of three strings
  • the range is between 160V and 311V, which greatly improves the working range of the voltage.
  • the voltage of the mains is high when the power load is small, and the voltage of the mains is low when the power load is large. This method can better cope with such harsh environments.
  • the LED can light up normally, and when the voltage is low, adjust the current of the light string, so that the luminous intensity of the light string is the same or similar to the luminous intensity of the normal voltage, and the power is also the same as the power when the voltage is normal. It can be consistent or similar, but the method of using a string of lights causes either no light or dim light because the voltage of the light string is high, and the current of the light string is constant.
  • the utility model can maintain the luminous intensity of the LED light string basically unchanged when the input voltage changes by setting at least two strings of LED light strings for driving control respectively. , and keep the power basically constant, and can also expand the working voltage range of the LED light string, thereby expanding the application range of the circuit.
  • the utility model also provides an LED constant power device correspondingly, which comprises a casing, a PCB board is arranged in the casing, and the above LED constant power circuit is arranged on the PCB board. Since the LED constant power circuit has been described in detail above, it will not be repeated here.
  • the present invention provides an LED constant power circuit and device, wherein the LED constant power circuit includes a constant current module, N LED light strings connected in series in sequence, and N-1 sampling adjustment modules connected in series in sequence, N is a positive integer greater than 1; among them, the N-1 sampling adjustment modules are also connected to the negative poles of the N-1 LED light strings respectively, and the negative pole of the Nth LED light string is connected to the constant current module, which is also connected to the constant current module.
  • the N-1th sampling adjustment module the utility model can effectively realize that the power of the LED lamp is relatively constant when the line voltage changes in a large range, and the luminous intensity of the LED lamp string remains unchanged.

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Abstract

本申请提供一种LED恒功率电路及装置，其中，LED恒功率电路包括恒流模块(200)、N个依次串联连接的LED灯串和N-1个采样调节模块(300)，N为大于1的正整数；其中，N-1个采样调节模块(300)还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块(200)，恒流模块(200)还连接第N-1个采样调节模块(300)；本申请能够有效实现在线电压大范围变化时LED灯具的功率相对恒定，LED灯串发光强度保持不变。

Description

一种LED恒功率电路及装置 技术领域
本实用新型涉及LED技术领域，特别涉及一种LED恒功率电路及装置。
背景技术
传统单段线性驱动LED应用中，整流桥输出的线电压大于LED灯串电压时，灯串有恒定电流流过，如图1a和1b，其电流是一个与线电压同周期的方波信号。一方面当输入交流电Vac增大引起线电压增大时，在恒流源的作用下LED灯串电流保持不变，导致功率增加，增加部分的功率将由线性驱动芯片承担，促使芯片温度升高，甚至损坏芯片；另一方面当输入交流电Vac减小引起线电压减小时，在恒流源的作用下LED灯串电流保持不变，导致功率降低，LED灯串发光变暗，甚至当线电压接近或低于LED灯串电压时，LED灯串将不发光，达不到照明的目的。
因而现有技术还有待改进和提高。
实用新型内容
鉴于上述现有技术的不足之处，本实用新型的目的在于提供一种LED恒功率电路及装置，能够实现在输入电压变化时保持功率的相对恒定。
为了达到上述目的，本实用新型采取了以下技术方案：
一种LED恒功率电路，包括恒流模块、N个依次串联连接的LED灯串和N-1个采样调节模块，N为大于1的正整数；其中，N-1个采样调节模块还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块，恒流模块还连接第N-1个采样调节模块；采样调节模块用于控制LED灯串点亮的数目，并控制流经对应LED灯串的电流，使得LED灯串点亮的数目与线电压的数值正相关，电流的数值与LED灯串点亮的数目负相关；恒流模块用于在N个LED灯串均点亮时，控制流经N个LED灯串的电流；其中N个LED灯串均点亮时的电流值小于前面N-1个LED灯串中任意一个 或多个点亮时的电流值。
所述LED恒功率电路中，每个采样调节模块包括恒流单元和采样单元；每个采样调节模块中的恒流单元分别与采样单元和对应LED灯串的负极连接；第一个至第N-2个采样调节模块中的采样单元对应与下一级采样调节模块中的恒流单元连接；第N-1个采样调节模块中的采样单元与恒流模块连接。
所述LED恒功率电路中，每个恒流单元包括第一运算放大器、第一电阻、第二电阻和第一MOS管；第一运算放大器的正相输入端连接第一参考电压输入端，第一运算放大器的反相输入端连接第一电阻的一端和采样单元，第一电阻的另一端连接第一MOS管的源极和第二电阻的一端，第二电阻的另一端接地，第一运算放大器的输出端连接第一MOS管的栅极，第一MOS管的漏极连接对应LED灯串的负极。
所述LED恒功率电路中，每个采样单元包括第二运算放大器、第二MOS管、第三电阻、第三MOS管和第四MOS管；第二运算放大器的正相输入端连接恒流模块或下一级恒流单元，第二运算放大器的反相输入端连接第三电阻的一端和第二MOS管的源极，第三电阻的另一端接地，第二MOS管的漏极连接第三MOS管的漏极、第四MOS管的栅极和第三MOS管的栅极，第二运算放大器的输出端连接第二MOS管的栅极，第三MOS管的源极和第四MOS管的源极均连接第二参考电压输入端，第四MOS管的漏极连接恒流单元。
所述LED恒功率电路中，所述恒流模块包括第三运算放大器、第五MOS管、第四电阻和第五电阻；所述第三运算放大器的正相输入端连接第三参考电压输入端，所述第三运算放大器的反相输入端连接第N-1个采样调节模块和第四电阻的一端，所述第四电阻的另一端连接第五MOS管的源极和第五电阻的一端，所述第五电阻的另一端接地，所述第五MOS管的漏极连接第N个LED灯串的负极
所述LED恒功率电路中，第一MOS管为N沟道MOS管。
所述LED恒功率电路中，第二MOS管为N沟道MOS管，第三MOS管和第四MOS管均为P沟道MOS管。
一种LED恒功率装置，包括外壳，外壳内设置有PCB板，PCB板上设置有上述 LED恒功率电路。
相较于现有技术，本实用新型提供的一种LED恒功率电路及装置，其中，LED恒功率电路包括恒流模块、N个依次串联连接的LED灯串和N-1个依次串联连接的采样调节模块，N为大于1的正整数；其中，N-1个采样调节模块还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块，恒流模块还连接第N-1个采样调节模块；本实用新型能够有效实现在线电压大范围变化时LED灯具的功率相对恒定，LED灯串发光强度保持不变。
附图说明
图1a和图1b为现有的LED控制电路的电路原理图以及电压信号和电流信号的波形图；
图2为本实用新型提供的LED恒功率电路的结构框图；
图3为本实用新型提供的LED恒功率电路的电路原理图。
具体实施方式
本实用新型提供的一种LED恒功率电路及装置，能够实现在输入电压变化时保持功率的相对恒定。
为使本实用新型的目的、技术方案及效果更加清楚、明确，以下参照附图并举实施例对本实用新型进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本实用新型，并不用于限定本实用新型。
请一并参阅图2和图3，本实用新型提供的一种LED恒功率电路，包括整流模块100、恒流模块200、N个依次串联连接的LED灯串和N-1个依次串联连接的采样调节模块300，N为大于1的正整数；其中，N-1个采样调节模块300还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块200，恒流模块200还连接第N-1个采样调节模块300；如图2所示，各个LED灯串分别为LED1、LED2、……LEDN，各个LED灯串串联连接，其中LED1的输入端连接整流模块100， 且前N-1个LED灯串的输出端均对应连接N-1个采样调节模块300。
具体实施时，整流模块100用于将交流电源输入的交流电整流后输出线电压(本实施例为Vin+)至LED灯串；采样调节模块300用于控制LED灯串点亮的数目，并控制流经对应LED灯串的电流，使得LED灯串点亮的数目与线电压的数值正相关，电流的数值与LED灯串点亮的数目负相关；恒流模块200用于在N个LED灯串均点亮时，控制流经N个LED灯串的电流；其中N个LED灯串均点亮时的电流数值小于前面N-1个LED灯串中任意一个或多个点亮时的电流，由此确保线电压增大时，LED灯串点亮的数目较多，流经LED灯串的电流较小，线电压减小时，LED灯串点亮的数目较少，而流经LED灯串的电流较大，根据功率P＝电压*电流，当电压升高时降低电流，进而实现线电压变化时功率相对恒定，使得LED灯串的发光强度基本不变。
具体来说，当线电压Vin+>Vled1时，第一个采样调节模块300会导通，LED1有电流Iled1流过点亮，其中电流Iled1由第一个采样调节模块300设置；当线电压Vin+>Vled1+Vled2时，第一个采样调节模块300会断开，第二个采样调节模块300导通，LED1和LED2串联后有电流ILed2流过，Iled2由第二个采样调节模块300设置；依次类推，当线电压Vin+>Vled1+Vled2+…+VledN-1时，第一个采样调节模块300至第N-2个采样调节模块300断开，第N-1个采样调节模块300导通，LED1、LED 2…以及LED N-1串联后有电流IledN-1流过，IledN-1由第N-1个采样调节模块300设置；当线电压Vin+>Vled1+Vled2+…+VledN时，第一个采样调节模块300至第N-1个采样调节模块300断开，恒流模块200导通，LED 1、LED2…以及LED N串联后有电流IledN流过，IledN由恒流模块200设置；其中，Vled1、Vled2…VledN对应各LED灯串电压，Iled1、Iled2…IledN-1对应各采样调节模块300设置的电流，IledN对应恒流模块200设置的电流，且Iled1>Iled2…>IledN-1>IledN；由此，当线电压降低时，控制较少的LED灯串点亮并且流过LED灯串电流较大，随着线电压升高时，点亮的LED灯串增加，流过灯串的电流减少，进而实现在线电压大范围变化时LED灯具的功率相对恒定，LED灯串发光强度基本不变，并且LED灯串被划分为多段，在输入的线电压较低时就能点亮，使得LED灯串点亮时间更长，适应的线电压范围更宽。
进一步地，每个采样调节模块300包括恒流单元310和采样单元320，也就是说N-1个采样调节模块300则分别有N-1个恒流单元310以及与恒流单元310对应的N-1采样单元320；每个采样调节模块300中的恒流单元310分别与采样单元320和对应LED灯串的负极连接；第一个至第N-2个采样调节模块300中的采样单元320对应与下一级采样调节模块300中的恒流单元310连接；第N-1个采样调节模块300中的采样单元320与恒流模块200连接；也就是说，第一个采样调节模块300中的采样单元320与第二个采样调节模块300中的恒流单元310连接，第二个采样调节模块300中的采样单元320与第三个采样调节模块300中的恒流单元310连接，依次类推，第N-2个采样调节模块300中的采样单元320与第N-1个采样调节模块300中的恒流单元310连接，第N-1个采样调节模块300中的采样单元320与则恒流模块200连接。
每个恒流单元310用于根据采样单元320输出的控制信号导通或断开，进而控制与该恒流单元310连接的LED灯串的电流的导通或断开，以实现对LED灯串点亮数目的调节；具体来说，当恒流单元310接收的控制信号的电压值大于第一参考电压，则恒流单元310断开，当恒流单元310接收的控制信号的电压值小于第一参考电压，则恒流单元310导通；而串联的N-1个采样单元320中，则是上一级采样单元320对下一级采样单元320输出的控制信号进行采样，根据采样的结果来输出控制信号控制本级恒流单元310的导通或断开，其中，第N-1个采样单元320则是根据恒流模块200的输入电压来控制第N-1个恒流单元310的导通或断开的，具体来说当采样单元320采样下一级采样单元320输出的控制信号得到的电压值大于预设电压，则对应的输出控制信号大于第一电压参考电压，当采样单元320采样下一级采样单元320输出的控制信号得到的电压值小于预设电压，则对应的输出控制信号小于第一参考电压；同样，第N-1个采样单元320采样输入电压得到的电压值大于预设电压时，对应输出的控制信号大于第一参考电压，第N-1个采样单元320采样输入电压得到的电压值小于预设电压时，对应输出的控制控制信号小于第一参考电压。
具体地，当线电压Vin+>Vled1时，第一个恒流单元310会导通，LED1有电流Iled1流过点亮，其中电流Iled1由第一恒流单元310设置；当线电压Vin+>Vled1+Vled2时， 第一恒流单元310会断开，第二个恒流单元310导通，LED1和LED2串联后有电流ILed2流过，Iled2由第二恒流单元310设置；依次类推，当线电压Vin+>Vled1+Vled2+…+VledN-1时，第一个恒流单元310至第N-2个恒流单元310断开，第N-1恒流单元310导通，LED1、LED 2…以及LED N-1串联后有电流IledN-1流过，IledN-1由第N-1个恒流单元310设置；当线电压Vin+>Vled1+Vled2+…+VledN时，第一个恒流单元310至第N-1个恒流单元310断开，恒流模块200导通，LED 1、LED2…以及LED N串联后有电流IledN流过，IledN由恒流模块200设置；其中，Vled1、Vled2…VledN对应各LED灯串电压，Iled1、Iled2…IledN-1对应各恒流单元310设置的电流，IledN对应恒流模块200设置的电流，且Iled1>Iled2…>IledN-1>IledN；由此确保线电压增大时，LED灯串点亮的数目较多，流经LED灯串的电流较小，线电压减小时，LED灯串点亮的数目较少，而流经LED灯串的电流较大，根据功率P＝电压*电流，当电压升高时降低电流，进而实现输入电压变化时功率相对恒定，使得LED灯串的发光强度基本不变。
请继续参阅图3，本实施例中以设置了三串串联连接的LED灯串为例对LED恒功率电路的工作原理进行具体说明，当然灯串串联的数目可依据需要进行设置，本实用新型对此不作限定；那么对应设置有两个恒流单元310和采样单元320，分别记采样单元320为采样单元1和采样单元2，恒流单元310为恒流单元1和恒流单元2，LED灯串为LED1、LED2和LED3。
输入交流电经整流模块100整流后输出线电压，Vin+接整流模块100输出正极，Vin-接整流模块100输出负极。Vled1、Vled2和Vled3分别为LED 1的电压、LED 2的电压和LED 3的电压，Iled1、Iled2和Iled3分别为恒流单元1设定的恒定电流、恒流单元2设定的恒定电流和恒流模块200设定的恒定电流。具体来说，Iled1为LED 1通过恒流单元1流到Vin-的电流，Iled2为LED 1和LED 2串联后通过恒流单元2流到Vin-的电流，Iled3为LED 1、LED2以及LED 3串联后通过恒流模块200流到Vin-的电流。
其中，每个恒流单元310包括第一电压源、第一运算放大器、第一电阻、第二电阻和第一MOS管；第一运算放大器的正相输入端连接第一电压源的正极，第一电压源的 负极接地，第一运算放大器的反相输入端连接第一电阻的一端和采样单元，第一电阻的另一端连接第一MOS管的源极和第二电阻的一端，第二电阻的另一端接地，第一运算放大器的输出端连接第一MOS管的栅极，第一MOS管的漏极连接对应LED灯串的负极，本实施例中第一MOS管为N沟道MOS管；其中，第一电压源用于为第一运算放大器的正相输入端提供第一参考电压，第一运算放大器的反相输入端用于接收对应采样单元输出的控制信号，控制第一MOS管的导通或断开；具体来说，当第一运算放大器比较出控制信号的电压值大于第一参考电压时，则控制第一MOS管断开，流过对应LED灯串的电流被关断，反之，则控制第一MOS管导通，对应LED灯串有对应电流流过。
本实施例中记两个恒流单元310中的第一运算放大器分别为OP1a和OP2a，第一MOS管分别为N1a和N2a，第一电阻分别为R1a和R2a，第二电阻分别为Rcs1和Rcs2，第一电压源分别为VR1a和VR2a，对应提供的第一参考电压分别为VREF1和VREF2；两个恒流单元310接收的控制信号分别为Ctrl1和Ctrl2。其中，第一电压源VR1a用于产生第一参考电压VREF1，Rcs1用于设定恒流单元1的电流，即流过LED 1的电流Iled1，Iled1＝VREF1/Rcs1，OP1a的反相输入端连接来自采样单元的控制信号Ctrl1，控制N1a的导通或断开，进而控制LED 1的电流导通或关断；即当Ctrl1的电压值大于VREF1时，OP1a输出信号断开N1a，流过LED 1的电流被关断，反之则N1a导通，LED 1有Iled1电流流过；其中，恒流单元2的原理与恒流单元1的原理相同，在此不做赘述。
进一步地，每个采样单元320包括第二电压源、第二运算放大器、第二MOS管、第三电阻、第三MOS管和第四MOS管；第二运算放大器的正相输入端连接恒流模块200或下一级恒流单元，第二运算放大器的反相输入端连接第三电阻的一端和第二MOS管的源极，第三电阻的另一端接地，第二MOS管的漏极连接第三MOS管的漏极、第四MOS管的栅极和第三MOS管的栅极，第二运算放大器的输出端连接第二MOS管的栅极，第三MOS管的源极和第四MOS管的源极均连接第二电压源的正极，第二电压源的负极接地，第四MOS管的漏极连接恒流单元；第二MOS管为N沟道MOS管，第三MOS管和第四MOS管均为P沟道MOS管。
本实施例中记两个采样单元320中的第二运算放大器分别为OP1b和OP2b，第二 MOS管分别为N1b和N2b，第三MOS管分别为P2和P4，第四MOS管分别为P1和P3，第三电阻分别为R1b和R2b，第二电压源分别为VR1b和VR2b，第二电压源用于提供第二参考电压VREF。
其中，OP1b的正相输入端连接OP2a的反相输入端，当Vin+电压大于Vled1+Vled2时，恒流单元2中的OP2a的反相输入端电压随Vin+电压升高至VREF2，采样单元1中的OP1b的正相输入端电压大于等于反相输入端电压，OP1b输出信号使得N1b导通，其中，OP1b的反相输入端电压对应预设电压，且该预设电压的电压值可通过设置第三电阻的阻值进行调节。Nb1导通后P1接着导通，那么就会有电流通过路径VREF->P1->R1a->Rcs1->Vin-流过，假设该电流为Ip1，则Ctrl1＝Ip1*(Rcs1+R1a)，电流Ip1由P1管、P2管、N1b管、电阻R1b、OP1b以及Ctrl2共同决定。本实用新型通过对Ip1、R1a和Rcs1进行合理取值，使得当有电流Ip1时，Ctrl1>VREF1，即OP1a的反相输入端电压大于正相输入端电压，恒流单元1断开，LED1没有电流通过恒流单元1流到Vin-。也就是采样单元1通过恒流单元2中OP2a的反相输入端电压Ctrl2来产生控制恒流单元1的Ctrl1，从而控制恒流单元1的电流断开或导通。而OP2b的正相输入端连接恒流模块200，那么采样单元2会通过恒流模块200的输入电压Ctrl3来产生控制恒流单元2的Ctrl2，从而控制恒流单元2的电流断开或导通。
进一步地，恒流模块200包括第三电压源、第三运算放大器、第五MOS管、第四电阻和第五电阻；第三运算放大器的正相输入端连接第三电压电压源的正极，第三电压源的负极接地，第三运算放大器的反相输入端连接第N-1个采样调节模块和第四电阻的一端，第四电阻的另一端连接第五MOS管的源极和第五电阻的一端，第五电阻的另一端接地，第五MOS管的漏极连接第N个LED灯串的负极，第五MOS管为N沟道MOS管。
本实施例中记第三电压源为VR3a，第三运算放大器为OP3a，第五MOS管为N3a，第四电阻为R3a，第五电阻为Rcs3；其中，采样单元2中OP2b的正相输入端连接OP3a的反相输入端，那么采样单元2会通过第三运算放大器的反相输入端的输入电压Ctrl3来产生控制恒流单元2的Ctrl2，从而控制恒流单元2的电流断开或导通；恒流模块200 在Vin+>Vled1+Vled2+Vled3时导通，其中，第三电压源VR3a用于产生第三参考电压VREF3，Rcs3用于设定恒流模块200的电流，即流过LED3的电流Iled3，Iled3＝VREF3/Rcs3。
当Vin+小于Vled1时，Ctrl1为低电平，N1a导通，随着Vin+升高至Vled1电压时，LED灯串1和N1a有电流Iled1流过，LED 1发光，LED 2及LED 3不发光；Vin+升高至大于Vled1+Vled2时，Ctrl2随之升高至VREF2，使得Ctrl1>VREF1，N1a关断，N2a导通，LED1、LED 2和N2a有电流Iled2流过，LED 1和LED 2同时发光，LED 3不发光；当Vin+继续升高至大于Vled1+Vled2+Vled3时，Ctrl3随之升高至VREF3，使得Ctrl2>VREF2，Ctrl1>VREF1，N1a关断，N2a关断，N3a导通，LED 1、LED2、LED 3和N3a有电流Iled3流过，LED灯串1、LED灯串2以及LED灯串3同时发光。在Vin+电压下降时同理，这里不做阐述。
其中，当Vin+>Vled1时，LED 1发光，其电流为Iled1＝VREF1/Rcs1，当Vin+>Vled1+Vled2时，LED 1和LED 2同时发光，其电流为Iled2＝VREF2/Rcs2，其中Iled2<Iled1,当Vin+>Vled1+Vled2+Vled3时，LED 1、LED 2和LED 3同时发光，其电流为Iled3＝VREF3/Rcs3，其中Iled3<Iled2<Iled1，通过预先设定Rcs1和Rcs2的电阻值来确定电流大小。根据功率P＝电压*电流，当电压升高时，同比例或者按固定值降低电流，可维持功率恒定或使其变化范围更小，使得驱动芯片承受的功率较少，以保护驱动芯片不被损坏。本实施例中，当Vin+>Vled1时，用较大的电流Iled1点亮LED 1，当Vin+升高，用较小的电流Iled2点亮LED1和LED2，当Vin+继续升高，用更小的电流Iled3点亮LED1、LED 2和LED 3。相比于电流恒定不变的驱动方法，功率变化范围更小，若想得到更小的功率变化，本实用新型中可增加LED灯串的数量，同时根据Vin+的电压值大小控制各LED灯串的电流来实现。
需要说明的是，本实施例中两个第一参考电压即VREF1和VREF2以及第三参考电压VREF3可合并为一个参考电压，即VREF1＝VREF2＝VREF3＝VREF0，也就是运算放大器OP1a、OP2a和OP3a的正相输入端连接到一起共用一个参考电压VREF0，根据灯串电流Iled＝VREF/Rcs，此时通过设定Rcs1<Rcs2<Rcs3，可得到Iled1>Iled2>Iled3的效 果。也可是三个参考电压不等，Rcs1、Rcs2和Rcs3共用一个恒流电阻Rcs，也就是运算放大器OP1a、OP2a和OP3a的反相输入端连接到一起共用一个恒流电阻Rcs到地，根据灯串电流Iled＝VREF/Rcs，此时通过设定VREF1>VREF2>VREF3，也可得到Iled1>Iled2>Iled3的效果。
进一步地，LED恒功率电路还包括储能模块400，储能模块400用于在线电压大于储能模块400的充电电压时存储电能，在线电压小于储能模块400的充电电压时释放电能，通过设置储能模块400可有效消除LED灯串的频闪。
具体地，储能模块400包括电容C1，电容C1的一端连接线电压输入端，电容C1的另一端接地；本实用新型通过设置储能模块400可根据LED灯串的工作电流选择合适的电容C1值，使得线电压Vin+的电压值在下降时，电容C1对LED灯串放电，一直持续到线电压Vin+再次大于电容C1电压，这样就能保证LED灯串发光不随线电压Vin+电压的变化，也就是无频闪或频闪深度比较低。
本实用新型通过设置至少两串LED灯串分别驱动，还可扩大LED灯串发光的工作电压范围。在此以设置三串LED灯串为例对本实用新型中可达到扩大LED灯串发光的工作电压范围的效果进行具体说明。本实施例中将LED灯串电压Vled0分为Vled1、Vled2和Vled3进行分别驱动，并且Vled1+Vled2+Vled3＝Vled0，可以看到，Vled1小于Vled0，对应的LED1在较低的Vin+就可发光，比如在220V的交流应用中，使用一串时Vled0为240V，使用三串时Vled1为160V，Vled2为40V，Vled2为40V，(Vled1、Vled2和Vled3也可为其它值，只要满足三者之和小于Vin+即可)220V交流电经整流模块整流后的Vin+为0V～311V间周期性变化的电压，使用一串的方法其点亮范围为240V～311V之间，而使用三串的方法其点亮范围为160V～311V之间，大大提高了电压的工作范围。在用电环境比较恶劣的国家和地区，其市电在用电负载小时电压偏高，用电负载大时其市电电压偏低，使用该方法更能应付这种恶劣环境，在其市电电压偏低时，LED能正常点亮发光，并且在电压偏低时调大灯串电流，使得灯串发光强度和正常电压时的发光强度一致或相近，并且功率和在电压正常时的功率也能保持一致或相近，而使用一串的方法因为灯串电压高，导致要么不发光，要么发光比较暗，并且灯串电流恒定 不变，在工作电压低时，不能调大灯串电流让灯串保持和正常电压时相同的亮度和功率；综上可知，本实用新型通过设置至少两串LED灯串进行分别驱动控制，能够实现在输入电压变化时可保持LED灯串的发光强度基本不变，并保持功率基本恒定，还可以扩大LED灯串工作电压范围，进而拓展了该电路的应用范围。
本实用新型还相应提供了一种LED恒功率装置，包括外壳，外壳内设置有PCB板，PCB板上设置有如上的LED恒功率电路。由于上文对该LED恒功率电路进行了详细描述，此处不再赘述。
综上，本实用新型提供的一种LED恒功率电路及装置，其中，LED恒功率电路包括恒流模块、N个依次串联连接的LED灯串和N-1个依次串联连接的采样调节模块，N为大于1的正整数；其中，N-1个采样调节模块还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块，恒流模块还连接第N-1个采样调节模块；本实用新型能够有效实现在线电压大范围变化时LED灯具的功率相对恒定，LED灯串发光强度保持不变。
可以理解的是，对本领域普通技术人员来说，可以根据本实用新型的技术方案及其实用新型构思加以等同替换或改变，而所有这些改变或替换都应属于本实用新型所附的权利要求的保护范围。

Claims (8)

  1. 一种LED恒功率电路，其特征在于，包括恒流模块、N个依次串联连接的LED灯串和N-1个采样调节模块，N为大于1的正整数；其中，N-1个采样调节模块还分别与N-1个LED灯串的负极对应连接，第N个LED灯串的负极连接恒流模块，恒流模块还连接第N-1个采样调节模块；采样调节模块用于控制LED灯串点亮的数目，并控制流经对应LED灯串的电流，使得LED灯串点亮的数目与线电压的数值正相关，电流的数值与LED灯串点亮的数目负相关；恒流模块用于在N个LED灯串均点亮时，控制流经N个LED灯串的电流；其中N个LED灯串均点亮时的电流值小于前面N-1个LED灯串中任意一个或多个点亮时的电流值。
  2. 根据权利要求1的LED恒功率电路，其特征在于，每个采样调节模块包括恒流单元和采样单元；每个采样调节模块中的恒流单元分别与采样单元和对应LED灯串的负极连接；第一个至第N-2个采样调节模块中的采样单元对应与下一级采样调节模块中的恒流单元连接；第N-1个采样调节模块中的采样单元与恒流模块连接。
  3. 根据权利要求2的LED恒功率电路，其特征在于，每个恒流单元包括第一运算放大器、第一电阻、第二电阻和第一MOS管；第一运算放大器的正相输入端连接第一参考电压输入端，第一运算放大器的反相输入端连接第一电阻的一端和采样单元，第一电阻的另一端连接第一MOS管的源极和第二电阻的一端，第二电阻的另一端接地，第一运算放大器的输出端连接第一MOS管的栅极，第一MOS管的漏极连接对应LED灯串的负极。
  4. 根据权利要求2的LED恒功率电路，其特征在于，每个采样单元包括第二运算放大器、第二MOS管、第三电阻、第三MOS管和第四MOS管；第二运算放大器的正相输入端连接恒流模块或下一级恒流单元，第二运算放大器的反相输入端连接第三电阻的一端和第二MOS管的源极，第三电阻的另一端接地，第二MOS管的漏极连接第三MOS管的漏极、第四MOS管的栅极和第三MOS管的栅极，第二运算放大器的输出端连接第二MOS管的栅极，第三MOS管的源极和第四MOS管的源极均连接第二参考电压输入端，第四MOS管的漏极连接恒流单元。
  5. 根据权利要求1的LED恒功率电路，其特征在于，所述恒流模块包括第三 运算放大器、第五MOS管、第四电阻和第五电阻；所述第三运算放大器的正相输入端连接第三参考电压输入端，所述第三运算放大器的反相输入端连接第N-1个采样调节模块和第四电阻的一端，所述第四电阻的另一端连接第五MOS管的源极和第五电阻的一端，所述第五电阻的另一端接地，所述第五MOS管的漏极连接第N个LED灯串的负极。
  6. 根据权利要求3的LED恒功率电路，其特征在于，第一MOS管为N沟道MOS管。
  7. 根据权利要求4的LED恒功率电路，其特征在于，第二MOS管为N沟道MOS管，第三MOS管和第四MOS管均为P沟道MOS管。
  8. 一种LED恒功率装置，包括外壳，外壳内设置有PCB板，其特征在于，PCB板上设置有如权利要求1-7任意一项的LED恒功率电路。
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