A PWM driving method for realizing high peak power of LED output

Abstract

The present application relates to a kind of PWM driving method for realizing LED output high peak power, selects adaptive LED device, definite its rated current I0, rated voltage U0 And maximum tolerance junction temperature, definite light peak power P demand;Build PWM driving device, cooperate with the conduction and cut-off of PWM pulse signal, so that LED device only in the high level stage of PWM pulse conduction, conduction time τ It is 0.1 μs~50 μs, in low level stage cut-off, no current passes through;The frequency of control PWM pulse, according to the demand of actual application scene, fine-tune PWM pulse conduction time τ And peak current I, I is actually adjusted voltage peak value, can further improve the peak power of output light, and make LED device maintain the parameter stable work.The present application realizes super high peak power output, guarantees LED safe and stable work, high flexibility, strong adaptability, simple structure, easy to realize.

Description

Technical Field

[0001] This invention belongs to the field of LED application technology, specifically relating to a PWM driving method for achieving high peak power output of LEDs, which is particularly suitable for high-energy phototherapy scenarios in the medical field. Background Technology

[0002] LEDs (light-emitting diodes) are widely used in lighting, display, and medical fields due to their advantages such as low energy consumption, long lifespan, and fast response speed. In the medical field, scenarios such as high-energy red light therapy and photodynamic therapy often require LEDs to output high peak power light signals to achieve precise control of cell metabolism, effective killing of pathogens, or rapid repair of damaged tissues.

[0003] In existing LED driving methods, to avoid damage from overheating, a rated current driving mode is typically used. This mode has limited output optical power, making it difficult to meet the high peak power optical signal requirements of the medical field. If the optical power is increased directly by increasing the driving current, when the current exceeds 2-3 times the rated current, the LED chip will rapidly generate a large amount of heat, causing a sharp rise in the chip junction temperature. This can lead to LED burnout within a short time, making long-term stable operation impossible. Even with a heatsink to control the temperature, excessive driving current will still burn out the LED.

[0004] PWM (Pulse Width Modulation) technology is a common method for LED dimming and power control. It controls the LED's on / off state by periodically switching between high and low voltage levels, thereby adjusting the average power. However, existing PWM driving methods mostly adjust the average power by changing the duty cycle. Their peak current is typically no greater than the rated current, or no more than five times the rated current, and the pulse width for light output is mostly in the millisecond range. This makes it difficult to balance high peak power with safe LED operation, and it is ill-suited to the high-energy transient light signal requirements of the medical field. Therefore, developing a PWM driving method for LEDs that can achieve ultra-high peak power output without damaging the LED has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies where LEDs are difficult to achieve high peak power output and are prone to burnout. It provides a PWM driving method to achieve high peak power output of LEDs. By optimizing PWM driving parameters and voltage control strategies, ultra-high peak power light output can be achieved while ensuring long-term stable operation of LEDs, thus meeting the application needs of the medical field.

[0006] This invention provides a PWM driving method for achieving high peak power output from an LED. The driving method is implemented through a PWM driving device, which consists of a signal generator, a power amplifier module, an LED device, a voltage regulation module, a current sampling module, and a temperature monitoring module. The output terminal of the signal generator is connected to the input terminal of the power amplifier module, the output terminal of the power amplifier module is connected to the input terminal of the LED device, the output terminal of the LED device is connected to the input terminal of the temperature monitoring module, the output terminal of the temperature monitoring module is connected to the input terminal of the signal generator, the output terminal of the LED device is connected to the input terminal of the current sampling module, the output terminal of the current sampling module is connected to the input terminal of the voltage regulation module, and the output terminal of the voltage regulation module is connected to the input terminal of the power amplifier module.

[0007] The LED device is driven by a PWM pulse signal. By applying a large-amplitude driving voltage to the two ends of the LED device, the peak value of the driving voltage (in fact, the LED driving voltage applied to the two ends of the LED device is also a PWM waveform) makes the current of the LED device in operation follow a PWM pulse mode, and meets the following two key technical characteristics:

[0008] (1) The peak current I of the LED device when it is working shall not be less than 10 times its rated current I0, that is, I≥10×I0;

[0009] (2) In the PWM waveform, the time (pulse width) for the LED device to be in the conducting state and generate light output is τ≤50μs, which can be adjusted to the range of 0.1μs~50μs according to actual needs;

[0010] The specific driving method is as follows:

[0011] (1) Select suitable LED devices, determine their rated current I0, rated voltage U0 and maximum withstand junction temperature, and determine the peak power P requirement;

[0012] (2) Build a PWM drive device. The drive circuit includes a signal generator, a power amplifier module and a set appropriate peak voltage (obtained through experiment or by using a voltage regulation module). The signal generator is used to generate a PWM pulse signal with a preset pulse width τ and frequency. The appropriate peak voltage is used to apply a sufficiently large drive voltage to the two ends of the LED to ensure that the LED can achieve the target peak current I≥10×I0 when it is turned on, and the light peak power is not less than the target peak power P.

[0013] (3) In coordination with the PWM pulse signal, the LED device is turned on only during the high level phase of the PWM pulse, with a conduction time τ of 0.1μs~50μs, and is turned off during the low level phase, with no current flowing through it;

[0014] (4) Control the frequency of the PWM pulse to keep the average power consumption of the LED device within its rated power consumption range, and ensure that the junction temperature of the LED device does not exceed the maximum tolerance junction temperature to avoid LED burnout;

[0015] (5) According to the needs of the actual application scenario, the PWM pulse conduction time τ and peak current I are finely adjusted. I is actually the peak value of the voltage adjustment, which can further improve the peak power of the output light and make the LED device maintain stable operation of this parameter.

[0016] In this invention, the peak power of the LED output light is ensured to reach a preset value by dynamically adjusting the driving peak voltage.

[0017] The specific adjustment logic is as follows: Monitor the peak power of the LED output light. If the peak power P is not greater than N times its rated power P0 (N is a preset value), continue to increase the driving peak voltage; if the peak power exceeds N times its rated power P0, use the current driving peak voltage to maintain stable LED operation. When increasing the peak voltage, the LED's conduction time can be reduced as needed to ensure that the LED does not burn out under higher current.

[0018] It should be noted that the key measures of this invention, which employ a peak current more than 10 times the rated driving current of the LED and control the LED's conduction time to a brief period of 0.1~50μs, are crucial for achieving high peak power output without burning out the LED. Therefore, although this invention is primarily presented in the form of PWM driving, any method that possesses these two core features, even if it uses a non-PWM driving method, falls within the scope of protection of this patent.

[0019] In this invention, the frequency range of the PWM pulse is 100Hz~10kHz, which can be flexibly adjusted according to the heat dissipation characteristics of the LED device and the application scenario requirements, ensuring that the average temperature of the LED device is within a safe range while achieving high peak power output.

[0020] In this invention, the LED device has a high thermal conductivity package structure and is used with a heat sink. The LED device is connected to the heat sink, which further improves heat dissipation efficiency, expands the adjustment range of pulse width and peak current, and adapts to the demand for higher peak power.

[0021] The present invention proposes an application of the PWM driving method for achieving high peak power output of LEDs in the medical field, which includes high-energy red light therapy, photodynamic therapy, chronic pain management, or nerve repair scenarios.

[0022] Compared with the prior art, the present invention has the following significant advantages:

[0023] (1) Achieve ultra-high peak power output: By applying a large value driving voltage to both ends of the LED and combining it with the PWM pulse driving mode, the peak current of the LED can reach more than 10 times the rated current, and the peak power of the light output can reach more than N times the rated power. This can meet the demand for high peak power light signals in high-energy phototherapy (such as high-energy red light therapy and photodynamic therapy) in the medical field. It can more efficiently stimulate the activity of cell mitochondria, kill pathogens or promote the repair of damaged tissues, and improve the treatment effect.

[0024] (2) Ensuring safe and stable operation of LEDs: By strictly controlling the conduction time of the PWM pulse (≤50μs, as low as 0.1μs), the conduction time of the LED is extremely short. Even with extremely high peak current, the heat generated per unit time can be controlled within a reasonable range. Combined with precise control of average power consumption, this effectively prevents the LED chip from burning out due to overheating. At the same time, the extreme conduction time also prevents excessive peak current from causing the LED to burn out. Therefore, it balances high power output with LED lifespan, solving the technical problem of "high peak power and safe LED operation being mutually exclusive" in the existing technology.

[0025] (3) High flexibility and strong adaptability: The PWM pulse width, peak current and driving frequency can be flexibly adjusted according to the parameters of different LED devices and actual application requirements. It can not only adapt to different models of LEDs, but also meet the differentiated needs of different treatment scenarios in the medical field (such as skin disease treatment, chronic pain management and nerve repair). It can also be extended to other fields that require high peak power transient light signals.

[0026] (4) Simple structure and easy to implement: No complex drive structure is required. High peak power output can be achieved by optimizing drive parameters and voltage control strategy. The drive circuit construction cost is low and it is easy to promote and apply on a large scale. Moreover, whether it is PWM or non-PWM drive mode, it can be implemented based on the core features of this invention, and the implementation difficulty is low. Attached Figure Description

[0027] Figure 1 This is a structural block diagram of the PWM driving device in Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the PWM waveform and current waveform of the LED in Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram comparing the peak power and rated power of an LED in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached diagram: 1-Signal generator, 2-Power amplifier module, 3-Voltage regulation module, 4-Current sampling module, 5-Temperature monitoring module, 6-LED device, 7-Heat sink. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can understand it.

[0032] Example 1

[0033] This embodiment provides a method for using PWM with high peak power LEDs for high-energy red light therapy in the medical field. The specific steps are as follows:

[0034] 1. Select a red LED (wavelength 630nm) with the following rated parameters: rated current I=20mA, rated voltage U=3V, rated output optical power P=0.03W, and maximum withstand junction temperature of 125℃. Determine the target peak current I=200mA (10 times the rated current) and the target peak optical power P=0.38 (12.7 times the rated power).

[0035] 2. Set up as follows Figure 1 The PWM drive device shown includes a signal generator 1, a power amplifier module 2, a voltage regulation module 3, a current sampling module 4, a temperature monitoring module 5, and an LED device 6. The LED device 6 adopts a high thermal conductivity package and is equipped with a heat sink 7. The signal generator 1 uses an STC89C52 microcontroller to generate PWM pulse signals. The power amplifier module 2 uses an SS8050 transistor to amplify the PWM signal to drive the LED device 6. The voltage regulation module 3 uses a DC-DC boost converter to adjust the driving voltage amplitude.

[0036] 3. Set the PWM pulse parameters through signal generator 1: pulse width τ = 20μs, frequency = 1kHz, that is, the period of the PWM pulse is 1ms, the LED conduction time is 20μs, and the cutoff time is 980μs;

[0037] 4. The driving voltage is adjusted to 15V by the voltage adjustment module 3 and applied to both ends of the LED device 6. When the PWM pulse is at a high level, the LED is turned on and the current rises rapidly to the peak current of 200mA, producing red light output; when the PWM pulse is at a low level, the LED is turned off, no current flows, and it stops emitting light.

[0038] 5. The peak current of the LED is detected in real time by the current sampling module 4. If the peak current is detected to be lower than 200mA, the voltage regulation module 3 automatically increases the driving voltage to ensure that the peak current is stable at 200mA. The junction temperature of the LED chip is detected in real time by the temperature monitoring module 5. The monitoring results show that the junction temperature of the LED is stable at 85℃ when it is working, which is lower than the maximum tolerance junction temperature of 125℃, and there is no risk of overheating.

[0039] 6. The test results show that the peak power of the LED output light is 0.39W, which exceeds the target light peak power and meets the requirements of high-energy red light therapy for high peak power light signals. It can be used to treat skin diseases such as acne and bedsores, and can effectively inhibit sebaceous gland secretion, kill Propionibacterium acnes, and accelerate the growth of granulation tissue in wounds.

[0040] Example 2

[0041] This embodiment provides a method for using PWM with high peak power LEDs for photodynamic therapy in the medical field. The specific steps are as follows:

[0042] 1. Select a blue LED (wavelength 415nm) with the following rated parameters: rated current I=10mA, rated voltage U=2.5V, rated output optical power P=0.013W, and maximum withstand junction temperature of 120℃. Determine the target peak current I=150mA (15 times the rated current) and the target peak power P=0.15W (approximately 12 times the rated optical power).

[0043] 2. Construct a PWM drive circuit with the same structure as in Example 1. The signal generator is an STM32 microcontroller, the power amplifier module is a MOSFET, and the voltage regulation module is an adjustable boost power supply.

[0044] 3. Set the PWM pulse parameters through the signal generator: pulse width τ = 0.1μs, frequency = 5kHz, that is, the period of the PWM pulse is 200μs, the LED conduction time is 0.1μs, and the cutoff time is 199.9μs;

[0045] 4. The driving voltage is adjusted to 16V by the voltage regulation module and applied to both ends of the LED device. When the PWM pulse is high, the LED is turned on and the current quickly reaches the peak current of 150mA, outputting high-intensity blue light; when the pulse is low, the LED is turned off and stops emitting light.

[0046] 5. Through real-time monitoring by the current sampling module and temperature monitoring module, the LED peak current is stable at 150mA and the chip junction temperature is stable at 78℃, which is lower than the maximum withstand junction temperature, and the operation is stable.

[0047] 6. The peak power of the blue LED output light is 0.155W, reaching the target rated light power. It can be used with photosensitizers for photodynamic therapy of skin cancers such as basal cell carcinoma. It can precisely activate the photosensitizer, selectively destroy cancer cells, and cause minimal damage to surrounding normal tissue, resulting in a high lesion clearance rate.

[0048] The above two embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PWM driving method for achieving high peak power output from an LED, characterized in that... The driving method is implemented through a PWM driving device, which consists of a signal generator, a power amplifier module, an LED device, a voltage regulation module, a current sampling module, and a temperature monitoring module. The output terminal of the signal generator is connected to the input terminal of the power amplifier module, the output terminal of the power amplifier module is connected to the input terminal of the LED device, the output terminal of the LED device is connected to the input terminal of the temperature monitoring module, the output terminal of the temperature monitoring module is connected to the input terminal of the signal generator, the output terminal of the LED device is connected to the input terminal of the current sampling module, the output terminal of the current sampling module is connected to the input terminal of the voltage regulation module, and the output terminal of the voltage regulation module is connected to the input terminal of the power amplifier module. The LED device is driven by a PWM pulse signal. By applying a large-amplitude driving voltage to the two ends of the LED device, the peak value of which is the actual LED driving voltage applied to the two ends of the LED device is also a PWM waveform. This makes the current of the LED device during operation follow a PWM pulse mode and meets the following two key technical characteristics: (1) The peak current I of the LED device when it is working shall not be less than 10 times its rated current I0, that is, I≥10×I0; (2) In the PWM waveform, the time (pulse width) for the LED device to be in the conducting state and generate light output is τ≤50μs, which can be adjusted to the range of 0.1μs~50μs according to actual needs; The specific driving method is as follows: (1) Select suitable LED devices, determine their rated current I0, rated voltage U0 and maximum withstand junction temperature, and determine the peak power P requirement; (2) Build a PWM driving device. The driving circuit includes a signal generator, a power amplifier module and a set appropriate peak voltage. The voltage is obtained through experimentation or by using a voltage regulation module. The signal generator is used to generate a PWM pulse signal with a preset pulse width τ and frequency. The appropriate peak voltage is used to apply a sufficiently large driving voltage to both ends of the LED to ensure that the LED can achieve the target peak current I≥10×I0 when it is turned on, and the light peak power is not less than the target peak power P. (3) In coordination with the PWM pulse signal, the LED device is turned on only during the high level phase of the PWM pulse, with a conduction time τ of 0.1μs~50μs, and is turned off during the low level phase, with no current flowing through it; (4) Control the frequency of the PWM pulse to keep the average power consumption of the LED device within its rated power consumption range, and ensure that the junction temperature of the LED device does not exceed the maximum tolerance junction temperature to avoid LED burnout; (5) According to the needs of the actual application scenario, the PWM pulse conduction time τ and peak current I are finely adjusted. I is actually the peak value of the voltage adjustment, which can further improve the peak power of the output light and make the LED device maintain stable operation of this parameter.

2. The PWM driving method for achieving high peak power output of an LED according to claim 1, characterized in that... By dynamically adjusting the driving peak voltage, the peak power of the LED output light is ensured to reach the preset value. The specific adjustment logic is as follows: Monitor the peak power of the LED output light. If the peak power P is not greater than N times its rated power P0 (where N is a preset value), then continue to increase the driving peak voltage. If the peak power exceeds N times its rated power P0, then use the current driving peak voltage to maintain stable LED operation. When increasing the peak voltage, the LED's conduction time can be reduced as needed to ensure that the LED does not burn out under higher current.

3. The PWM driving method for achieving high peak power output of an LED according to claim 1, characterized in that... The frequency range of the PWM pulse is 100Hz~10kHz, which can be flexibly adjusted according to the heat dissipation characteristics of the LED device and the application scenario requirements, ensuring that the average temperature of the LED device is within a safe range while achieving high peak power output.

4. The PWM driving method for achieving high peak power output of an LED according to claim 1, characterized in that... The LED device has a high thermal conductivity package structure and is used with a heat sink. The LED device is connected to the heat sink, which further improves heat dissipation efficiency, expands the adjustment range of pulse width and peak current, and adapts to the demand for higher peak power.

5. The PWM driving method for achieving high peak power output of an LED according to claim 1, characterized in that... The proposed PWM driving method for achieving high peak power output of LEDs has applications in the medical field, including high-energy red light therapy, photodynamic therapy, chronic pain management, or nerve repair scenarios.

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