High-power Light-emitting Diode Lighting Research Articles

Novel distortionless dimming in high power LED lighting using isolated SEPIC converter

A new low-cost energy-saving concept in the modern light-emitting diode (LED) illumination system is developed and implemented using an isolated single-ended primary inductance converter (SEPIC). The dimming scheme presented in this study is a single-step with negligible distortion in the AC mains current as compared to the traditional low-cost triode for alternating current (TRIAC) dimming system, which distorts the AC mains current wave-shape beyond sinusoidal nature due to the phase-cut techniques. This dimming concept is completely retrofitted, no additional arrangement is required to initiate the dimming as compared to a TRIAC dimmer or other controllers. The isolated SEPIC converter is modelled and analysed in detail using the state-space average technique. The stability of the designed converter and overall closed-loop control are verified using Bode-plot analysis. The full load converter efficiency is found around 93%, which is much higher than the conventional flyback topology-based LED driver. The concept presented in this study is tested with the help of a laboratory prototype with an LED load of 60 W.

Possibility of Thermal Energy Recycling Based Light Emitting Diodes Grid System

Light Emitting Diodes (LED) are highly energy efficient and offer long-life times for display applications. Long life and minimal energy consumption are often the most attractive advantages for electronic devices. Because LEDs are based on compound semiconductors, which explore the direct transition between the conduction and valance band edges, thermal energy loss can be minimized during operation. However, even though these types of LEDs are based on direct transition type semiconductors, thermal energy is still emitted during operation owing to forward conduction and reverse leakage currents. This research proposes capturing this energy loss through thermoelectric module-based energy recycling methods to improve the energy efficiency of LED applications, achieving savings of up to 18%. Additional analysis was performed on high power LED sources resulting in the manufacture of a high-power LED light grid system.

High Power Factor Light-emitting Diode Driver on Digital Signal Processor Without Electrolytic Capacitor for High-power Lighting

—Electrolytic capacitor is a key factor that limits the life-time of the driver in a high-power light-emitting diode (LED) lighting. This article presents a high-power LED lighting driver on a digital signal processor without an electrolytic capacitor. The driver is composed of three stage circuits. The first stage is the boost power factor correction converter to achieve a high power factor. As it does not use an electrolytic capacitor, the output voltage ripple is larger, which directly affects the overall performance of the LED driver. Consequently, it must be optimized through the second and third stages. The second stage is the two-output LLC (Double inductance and capacitance) resonant converter, which is driven by a digital signal processor. This stage provides galvanic isolation and reduces voltage. The third stage is the two-input buck converter based on digital signal processor control that reduces the low-frequency ripple generated from the first two stages. Moreover, the regulation of each LED string current is achieved at this stage. The simulation and experimental results show that this LED lighting driver can achieve a high power factor and good constant current characteristics.

Study on thermal and structural stability of high power light-emitting diode lighting system.

In this paper, we have been analyzed the thermal-fluid flow and structural stress of high power Light-emitting diode (LED) lighting system for outdoor lighting. Thermal and Structural performances of LED lighting systems were designed using computer aided engineering (CAE) and after securing their structural and thermal safety, simulated in order to develop 400 W high-efficiency LED floodlight. The temperature of LED was shown to rise up to 136 degrees C. This means that the cooling system should be improved. Maximum strain was detected in the glass, yet they appeared largely safe. It is important for the design to focus on the cooling fin. Regarding the lifespan of LED, it is necessary to have a plan for minimizing errors when testing designs for optimizing air-cooling structures. Which measured the lifetime of the lighting equipment has passed.

Cooling of high power LEDs through ventilating ambient air to front surface of chip

In this study, a novel cooling strategy through ventilating ambient air to the front surface of the hot chips of the high power light-emitting diodes (LEDs) was proposed to tackle the ever tough issues facing the conventional thermal management approaches. Preliminary thermal resistance analysis, numerical simulation and conceptual experiments were carried out to evaluate the cooling performance thus enabled. In the system analysis, a thermal network model was established to characterize the thermal resistance of an ordinary high power LED light and that of the newly proposed light module. Through ventilating the high speed ambient airflow directly onto the chip surface, the thermal resistance of the whole light could be evidently reduced and additional pathway was thus opened for releasing heat from the chips. Further, three-dimensional finite volume simulations were adopted to investigate the temperature distribution of the new light. It was found that even without heat sink or active cooling at the back part of the LED light, the new method via cooling the front part still works well. Lastly, a conceptual experiment was performed, which again demonstrated that cooling the LED at its front surface suggests an effective way to maintain the safe running of LED light within an allowable temperature scale just as cooling the light at the back part. The present method initiates a new way for future thermal management of high power LEDs.

Ceramic-metal package for high power LED lighting

High power light-emitting diodes (LEDs) lighting has drawn a great interest in the field of street light system in recent years. Key parameters for successful launching of LED street light in the commercial market are price and light efficiency, respectively, and they are greatly influenced by the materials and design factors used in high power LED package. This article presents a new design and materials processing technology to realize the solution of LED packaging with advantageous in price and performance. Cost effective materials and processing technology can be realized via thick film glass-ceramic insulating layer and silver conductor. Highly effective thermal design using direct heat dissipation to heat sink in LED package is demonstrated.

Modeling of dimmable High Power LED illumination distribution using ANFIS on the isolated area

High power light emitting diodes (HP-LEDs) are more suitable for energy saving applications and have becoming replacing traditional fluorescent and incandescent bulbs for its energy efficient. Therefore, HP-LED lighting has been regarded in the next-generation lighting. In this study, illumination distribution of white color HP-LED is modeled by adaptive neuro-fuzzy inference system (ANFIS) approach on the isolated area while LED head is fixed. Subtractive clustering with hybrid learning approach is used to train the realized ANFIS architectures. End of the numerous experiment we finally concluded that, ANFIS could be used to modeling the illumination distribution applications perfectly.