LED drive circuit and LED power supply

Abstract

The present invention belongs to the field of power supply technology and provides an LED drive circuit and an LED power supply. The LED drive circuit is connected to an LED module and includes: a first sampling module, a second sampling module, a reference voltage generation module, a feedback module, a control module, and a voltage conversion module. The first sampling module is configured to generate a voltage sampling signal based on a driving power supply; the second sampling module is configured to generate a current sampling signal based on the driving power supply; the reference voltage generation module is configured to generate a first reference voltage based on the voltage sampling signal; the feedback module is configured to generate a feedback signal based on the first reference voltage and the current sampling signal; the control module is configured to generate a control signal based on the feedback signal; and the voltage conversion module is configured to convert an input voltage into a driving power supply based on the control signal to drive the LED module.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supplies, and in particular relates to an LED drive circuit and an LED power supply. Background Art

[0002] The forward voltage (VF) of different LED light sources varies significantly. Even for the same LED light source combination, VF can vary significantly between batches or manufacturers. Therefore, using a standard constant-current power supply can lead to significant variations in input power for LED lamps within the same batch. Even greater variations in VF are seen when different LED light source combinations are connected in series or parallel, necessitating the use of power supplies with multiple current specifications to meet these requirements. This requires customers to prepare multiple power supply specifications, increasing costs. Selecting a power supply can also be challenging, requiring professional testing equipment to accurately match the LEDs to the power supply.

[0003] Currently, constant power designs on the market all use microcontroller units (MCUs). Two MCU pins detect the power supply drive voltage and output current. Through MCU multiplication operations, the corresponding pulse width modulation (PWM) signal is output to the control loop to achieve constant output power adjustment. Therefore, the circuit needs to add an MCU and its power supply circuit, which leads to complex circuits. Moreover, personnel who understand digital and analog circuits are required to implement power supply development. The design and development is very difficult. As the number of components used in the power supply increases, the corresponding cost will also increase significantly.

[0004] Therefore, the traditional constant power drive technology solution has the problems of high difficulty in circuit development and increased cost. Summary of the Invention

[0005] The object of the present invention is to provide an LED driving circuit and an LED power supply, aiming to solve the problems of high circuit development difficulty and increased cost in traditional constant power driving technology solutions.

[0006] An LED driving circuit is connected to an LED module, and the LED driving circuit includes:

[0007] A first sampling module for generating a voltage sampling signal according to a driving power supply;

[0008] a second sampling module for generating a current sampling signal according to the driving power supply;

[0009] a reference voltage generating module connected to the first sampling module and configured to generate a first reference voltage according to the voltage sampling signal;

[0010] a feedback module connected to the second sampling module and the reference voltage generating module, and configured to generate a feedback signal according to the first reference voltage and the current sampling signal;

[0011] a control module connected to the feedback module and configured to generate a control signal according to the feedback signal;

[0012] A voltage conversion module connected to the control module is used to convert the input voltage into a driving power supply to drive the LED module according to the control signal.

[0013] In one embodiment, it further includes:

[0014] An input module connected to the voltage conversion module, used to generate an input voltage according to the input mains power supply.

[0015] In one embodiment, the input module includes:

[0016] A low-pass filtering unit for performing low-pass filtering on the mains power;

[0017] A rectifier and filter unit connected to the low-pass filter unit, configured to generate the input voltage according to the mains power after low-pass filtering.

[0018] In one embodiment, the first sampling module includes: a first sampling resistor and a second sampling resistor;

[0019] The first end of the first sampling resistor is a driving power input end of the first sampling module, the second end of the first sampling resistor is grounded through the second sampling resistor, and the common terminal of the first sampling resistor and the second sampling resistor is a voltage sampling signal output end of the first sampling module.

[0020] In one embodiment, the second sampling module includes: a third sampling resistor, a fourth sampling resistor and a fifth sampling resistor;

[0021] The first end of the third sampling resistor is the driving power input end of the second sampling module, the second end of the third sampling resistor is connected to the LED module, the first end of the fourth sampling resistor is connected to the first end of the third sampling resistor, the first end of the fifth sampling resistor is connected to the second end of the third sampling resistor, and the second end of the fourth sampling resistor and the second end of the fifth sampling resistor are the current sampling signal output ends of the second sampling module.

[0022] In one embodiment, the reference voltage generating module includes: a first operational amplifier, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

[0023] The non-inverting terminal of the first operational amplifier is the second reference voltage input terminal of the reference voltage generation module, the inverting terminal of the first operational amplifier is the voltage sampling signal input terminal of the reference voltage generation module, the output terminal of the first operational amplifier is connected to the first end of the first resistor, the second end of the first resistor is connected to the second reference voltage through the second resistor, the second end of the first resistor is connected to the first end of the fourth resistor through the third resistor, the first end of the fourth resistor is grounded through the fifth resistor, the second end of the fourth resistor is grounded through the first capacitor, the second end of the fourth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is the first reference voltage output terminal of the reference voltage generation module.

[0024] In one embodiment, the feedback module includes: a second operational amplifier;

[0025] The non-inverting terminal of the second operational amplifier is the first reference voltage input terminal of the feedback module, the inverting terminal of the second operational amplifier and the non-inverting terminal of the second operational amplifier are the current sampling signal input terminals of the feedback module, and the output terminal of the second operational amplifier is the feedback signal output terminal of the feedback module.

[0026] In one embodiment, it further includes:

[0027] an auxiliary power supply module connected to the input module and configured to generate an auxiliary voltage according to the input voltage;

[0028] The control module specifically generates a control signal according to the auxiliary voltage and the feedback signal; the auxiliary power supply module includes: a power conversion chip and a first transformer;

[0029] The first end of the primary coil of the first transformer is the input voltage input end of the auxiliary power supply module, the control end of the power conversion chip is connected to the second end of the primary coil of the first transformer, the first end of the secondary coil of the first transformer is the auxiliary voltage output end of the auxiliary power supply module, and the second end of the secondary coil of the first transformer is grounded.

[0030] In one embodiment, the control module includes a control unit, a photoelectric isolator, and a first diode;

[0031] The cathode of the first diode is the feedback signal input terminal of the control module, the anode of the first diode is connected to the cathode of the light emitter of the photoelectric isolator, the anode of the light emitter of the photoelectric isolator is the auxiliary voltage input terminal of the control module, the first end of the light receiving end of the photoelectric isolator is connected to the feedback end of the control unit, and the second end of the light receiving end of the photoelectric isolator is grounded.

[0032] In addition, an LED power supply and the LED module are also provided. The LED power supply includes: the above-mentioned LED driving circuit.

[0033] The above-mentioned LED driving circuit samples the driving power supply through the first sampling module and generates a voltage sampling signal. The feedback module generates a first reference voltage based on the voltage sampling signal. At the same time, the driving power supply is sampled by the second sampling module to generate a current sampling signal. The reference voltage generation module generates a first reference voltage based on the voltage sampling signal. The feedback module generates a feedback signal based on the first reference voltage and the current sampling signal. The control module generates a control signal based on the feedback signal. The control voltage conversion module converts the input voltage into a driving power supply to drive the LED module. When the load is changed, the power of the driving power supply changes. The voltage sampling signal and the current sampling signal are used to detect the voltage change and the current change of the driving power supply, and a feedback signal is generated based on the voltage change and the current change of the driving power supply, thereby realizing constant power output of the circuit, improving the adaptability of the power supply, simplifying the circuit, reducing development difficulty, and reducing power supply cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram of an LED driving circuit provided in an embodiment of the present invention;

[0035] Figure 2 for Figure 1 The schematic diagram of the structure of the input module in the LED drive circuit shown;

[0036] Figure 3 for Figure 1 Part of the example circuit schematic diagram of the LED driver circuit shown;

[0037] Figure 4 This is an example circuit schematic diagram of the auxiliary power module in the LED drive circuit. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] Figure 1 FIG. 1 shows a schematic diagram of the structure of the LED driving circuit provided by an embodiment of the present invention. Figure 1As shown, the LED driving circuit is connected to the LED module 2 and includes: a first sampling module 10, a second sampling module 20, a reference voltage generating module 30, a feedback module 40, a control module 50, and a voltage conversion module 60. The first sampling module 10 is used to generate a voltage sampling signal based on the driving power supply; the second sampling module 20 is used to generate a current sampling signal based on the driving power supply; the reference voltage generating module 30 is connected to the first sampling module 10 and is used to generate a first reference voltage based on the voltage sampling signal; the feedback module 40 is connected to the second sampling module 20 and the reference voltage generating module 30 and is used to generate a feedback signal based on the first reference voltage and the current sampling signal; the control module 50 is connected to the feedback module 40 and is used to generate a control signal based on the feedback signal; and the voltage conversion module 60 is connected to the control module 50 and is used to convert the input voltage into a driving power supply based on the control signal to drive the LED module.

[0040] In this embodiment, the driving power supply is sampled by the first sampling module 10 and a voltage sampling signal is generated. The feedback module 40 generates a first reference voltage based on the voltage sampling signal. At the same time, the driving power supply is sampled by the second sampling module 20 to generate a current sampling signal. The reference voltage generation module 30 generates a first reference voltage based on the voltage sampling signal. The feedback module 40 generates a feedback signal based on the first reference voltage and the current sampling signal. The control module 50 generates a control signal based on the feedback signal. The control voltage conversion module 60 converts the input voltage into a driving power supply to drive the LED module. When the load is changed, the power of the driving power supply changes. The voltage sampling signal and the current sampling signal are used to detect the voltage change and the current change of the driving power supply, and a feedback signal is generated based on the voltage change and the current change of the driving power supply, thereby achieving constant power output of the circuit, improving the adaptability of the power supply, simplifying the circuit, reducing development difficulty, and reducing power supply cost.

[0041] In one embodiment, the LED driver circuit further includes an input module 70, which is connected to the voltage conversion module 60 and is configured to generate an input voltage based on the input mains power supply. In one embodiment, the input module 70 includes a low-pass filter unit 71 and a rectifier filter unit 72. The low-pass filter unit 71 is configured to perform low-pass filtering on the mains power; the rectifier filter unit 72 is connected to the low-pass filter unit 71 and is configured to generate an input voltage based on the low-pass filtered mains power.

[0042] like Figure 2As shown, in one embodiment, the reference voltage generating module 30 includes a first operational amplifier U1, a first capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; the non-inverting terminal of the first operational amplifier U1 is the second reference voltage input terminal of the reference voltage generating module 30, the inverting terminal of the first operational amplifier U1 is the voltage sampling signal input terminal of the reference voltage generating module 30, the output terminal of the first operational amplifier U1 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the second reference voltage through the second resistor R2, the second end of the first resistor R1 is connected to the first end of the fourth resistor R4 through the third resistor R3, the first end of the fourth resistor R4 is grounded through the fifth resistor R5, the second end of the fourth resistor R4 is grounded through the first capacitor C1, the second end of the fourth resistor R4 is connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is the first reference voltage output terminal of the reference voltage generating module 30.

[0043] In one embodiment, the feedback module 40 includes a second operational amplifier U2; the non-phase terminal of the second operational amplifier U2 is the first reference voltage input terminal of the feedback module 40, the inverting terminal of the second operational amplifier U2 and the non-phase terminal of the second operational amplifier are the current sampling signal input terminals of the feedback module 40, and the output terminal of the second operational amplifier U2 is the feedback signal output terminal of the feedback module 40.

[0044] In one embodiment, the control module 50 includes a control unit, a photoisolator U3, and a first diode D1. The cathode of the first diode D1 serves as the feedback signal input terminal of the control module 50. The anode of the first diode D1 is connected to the cathode of the light emitter of the photoisolator U3. The anode of the light emitter of the photoisolator U3 serves as the auxiliary voltage input terminal of the control module 50. The first light-receiving terminal of the photoisolator U3 is connected to the feedback terminal of the control unit, and the second light-receiving terminal of the photoisolator U3 is grounded. The control unit includes a switching power supply chip, and the power conversion module includes a transformer.

[0045] In one embodiment, the first sampling module 10 includes a first sampling resistor R7 and a second sampling resistor R8; the first end of the first sampling resistor R7 is a driving power input end of the first sampling module 10, the second end of the first sampling resistor R7 is grounded through the second sampling resistor R8, and the common terminal of the first sampling resistor R7 and the second sampling resistor R8 is a voltage sampling signal output end of the first sampling module 10.

[0046] In one embodiment, the second sampling module 20 includes a third sampling resistor R9, a fourth sampling resistor R10, and a fifth sampling resistor R11; the first end of the third sampling resistor R9 serves as a driving power input terminal of the second sampling module 20, the second end of the third sampling resistor R9 is connected to the LED module 2, the first end of the fourth sampling resistor R10 is connected to the first end of the third sampling resistor R9, the first end of the fifth sampling resistor R11 is connected to the second end of the third sampling resistor R9, and the second end of the fourth sampling resistor R10 and the second end of the fifth sampling resistor R11 serve as current sampling signal output terminals of the second sampling module 20.

[0047] like Figure 3 As shown, in one embodiment, the LED driving circuit further includes an auxiliary power supply module 80, which is connected to the input module 10 and is configured to generate an auxiliary voltage based on the input voltage. In one embodiment, the auxiliary power supply module 80 includes a power conversion chip U4 and a first transformer T1. The first end of the primary coil of the first transformer T1 serves as the input voltage input terminal of the auxiliary power supply module 80. The control terminal LX of the power conversion chip U4 is connected to the second end of the primary coil of the first transformer T1. The first end of the secondary coil of the first transformer T1 serves as the auxiliary voltage output terminal of the auxiliary power supply module 80. The second end of the secondary coil of the first transformer T1 is grounded.

[0048] In addition, an LED power supply is provided, which is connected to the LED module 2. The LED power supply includes: the above-mentioned LED driving circuit.

[0049] The following circuit principle Figure 2 To explain:

[0050] There are large differences in the forward voltages of different LED light sources. When the LED module 2 connected to the LED driving circuit changes, the driving power output by the LED driving circuit will also change, thereby failing to meet the requirement of constant power output.

[0051] Therefore, in this embodiment, when the LED module 2 connected to the LED driving circuit changes, the driving voltage is sampled through the first sampling resistor R7 and the second sampling resistor R8 to generate a voltage sampling signal. The first operational amplifier U1 generates a first reference voltage based on the voltage sampling signal, and outputs it to the non-inverting terminal of the second operational amplifier U2 through the first capacitor C1, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6. The second operational amplifier U2 generates a feedback signal based on the first reference voltage and the current sampling signal, and outputs it to the feedback terminal of the control module 50 through the photoelectric isolator U3. The control module 50 outputs a control signal based on the feedback signal to control the voltage conversion module to generate a constant-power driving power supply.

[0052] Specifically, when the LED module 2 changes, causing the driving power supply to change from the first load to the second load, the voltage of the driving power supply changes from the original driving voltage U1 to the non-steady-state driving voltage U2', and the current of the driving power supply changes from the original driving current I1 to the non-steady-state driving current I2'. The first sampling module 10 and the second sampling module 20 respectively sample the non-steady-state driving voltage U2' and the non-steady-state driving current I2' to generate a voltage sampling signal and a current sampling signal, respectively. The first operational amplifier U1 generates a corresponding first reference voltage based on the voltage sampling signal, and the second operational amplifier U2 generates a feedback signal based on the first reference voltage and the current sampling signal. The control module 50 generates a changed control signal based on the feedback signal to control the voltage conversion unit to output a new driving power supply, wherein the product of the target driving voltage U2 of the new driving power supply and the target driving current I2 of the new driving power supply (i.e., the power of the new driving power supply) is equal to the product of the original driving voltage U1 and the original driving current I1 (i.e., the power of the driving power supply under the first load), thereby achieving constant power output of the circuit and improving the adaptability of the power supply.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An LED driving circuit connected to an LED module, characterized in that: The LED driving circuit includes: A first sampling module for generating a voltage sampling signal according to a driving power supply; a second sampling module for generating a current sampling signal according to the driving power supply; a reference voltage generating module connected to the first sampling module and configured to generate a first reference voltage according to the voltage sampling signal; a feedback module connected to the second sampling module and the reference voltage generating module, and configured to generate a feedback signal according to the first reference voltage and the current sampling signal; a control module connected to the feedback module and configured to generate a control signal according to the feedback signal; A voltage conversion module connected to the control module and configured to convert an input voltage into a driving power supply to drive the LED module according to a control signal; An input module connected to the voltage conversion module and configured to generate an input voltage according to an input mains power supply; an auxiliary power supply module connected to the input module and configured to generate an auxiliary voltage according to the input voltage; The control module specifically generates a control signal according to the auxiliary voltage and the feedback signal; the auxiliary power supply module includes: a power conversion chip and a first transformer; A first end of the primary coil of the first transformer is an input voltage input terminal of the auxiliary power module, a control terminal of the power conversion chip is connected to a second end of the primary coil of the first transformer, a first end of the secondary coil of the first transformer is an auxiliary voltage output terminal of the auxiliary power module, and a second end of the secondary coil of the first transformer is grounded; The control module includes a control unit, a photoelectric isolator and a first diode; The cathode of the first diode is the feedback signal input terminal of the control module, the anode of the first diode is connected to the cathode of the light emitter of the photoelectric isolator, the anode of the light emitter of the photoelectric isolator is the auxiliary voltage input terminal of the control module, the first end of the light receiving end of the photoelectric isolator is connected to the feedback end of the control unit, the second end of the light receiving end of the photoelectric isolator is grounded, and the control unit includes a switching power supply chip.

2. The LED driving circuit according to claim 1, wherein: The input module includes: A low-pass filtering unit for performing low-pass filtering on the mains power; A rectifier and filter unit connected to the low-pass filter unit, configured to generate the input voltage according to the mains power after low-pass filtering.

3. The LED driving circuit according to claim 1, wherein: The first sampling module includes: a first sampling resistor and a second sampling resistor; The first end of the first sampling resistor is a driving power input end of the first sampling module, the second end of the first sampling resistor is grounded through the second sampling resistor, and the common terminal of the first sampling resistor and the second sampling resistor is a voltage sampling signal output end of the first sampling module.

4. The LED driving circuit according to claim 1, wherein: The second sampling module includes: a third sampling resistor, a fourth sampling resistor and a fifth sampling resistor; The first end of the third sampling resistor is the driving power input end of the second sampling module, the second end of the third sampling resistor is connected to the LED module, the first end of the fourth sampling resistor is connected to the first end of the third sampling resistor, the first end of the fifth sampling resistor is connected to the second end of the third sampling resistor, and the second end of the fourth sampling resistor and the second end of the fifth sampling resistor are the current sampling signal output ends of the second sampling module.

5. The LED driving circuit according to claim 1, wherein: The reference voltage generating module includes: a first operational amplifier, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor; The non-inverting terminal of the first operational amplifier is the second reference voltage input terminal of the reference voltage generation module, the inverting terminal of the first operational amplifier is the voltage sampling signal input terminal of the reference voltage generation module, the output terminal of the first operational amplifier is connected to the first end of the first resistor, the second end of the first resistor is connected to the second reference voltage through the second resistor, the second end of the first resistor is connected to the first end of the fourth resistor through the third resistor, the first end of the fourth resistor is grounded through the fifth resistor, the second end of the fourth resistor is grounded through the first capacitor, the second end of the fourth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is the first reference voltage output terminal of the reference voltage generation module.

6. The LED driving circuit according to claim 1, wherein: The feedback module includes: a second operational amplifier; The non-inverting terminal of the second operational amplifier is the first reference voltage input terminal of the feedback module, the inverting terminal of the second operational amplifier and the non-inverting terminal of the second operational amplifier are the current sampling signal input terminals of the feedback module, and the output terminal of the second operational amplifier is the feedback signal output terminal of the feedback module.

7. An LED power supply connected to the LED module, characterized in that: The LED power supply comprises: the LED driving circuit according to any one of claims 1 to 6.

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