Rapid voltage and current changes in recently ubiquitous LED driver have a potency to interfere other devices. Some solutions with special converter design, component design, EMI filter, and spread-spectrum techniques have been proposed. Due to cost-size-weight constraints, the spread-spectrum technique seems to be a potential candidate in alleviating EMI problem in LED application. In this paper, the effectiveness of conducted EMI suppression performance of the spread-spectrum technique is evaluated. Spread spectrum techniques applied by giving disturbance to the LED driver system with three profile signals, filtered square, triangular, and sine disturbance signal to the switching pattern of a buck LED driver topology. From the experiment results, 472.5 kHz triangular and 525 kHz sine signal can reduce EMI by 42 dB while the filtered square signal can reduce EMI 40.70 dB compared to fundamental constant-frequency reference 669 kHz. The filtered square signal can reduce the average power level better than other signal disturbance of 5.852618 dBµV. LED luminance decreases when the spread-spectrum technique is applied to the system. . To achieve high efficiency in energy transfer, switched-mode power supply (SMPS) topology is applied, such as buck, boost, flyback, cuk dan buck-boost [11]- [22]. In addition, the SMPS is widely applied due to the benefits offered in terms of size, weight, cost and performance. SMPS is usually implemented using pulse width modulation (PWM). PWM operates at a constant frequency. The weakness of this system is the fundamental and harmonic frequencies emitted through conducted and radiated mechanism. This emission is called electromagnetic interference (EMI). As a result, the potential converter does not meet the standards of electromagnetic compatibility (EMC) [11],[14][23], [24].SMPS has a periodic switching pattern, i.e. EMI spectrum which consists of the fundamental and harmonic frequencies with significant amplitudes up to the 20th harmonic [25]. This condition could probably pass the limit set by the conducted EMI CISPR 22 Class B standards. Some solutions are used to reduce EMI issues in LED drivers, including the converter designs [12] [39]. Of all these solutions, the spread-spectrum technique is a solution that is inexpensive and efficient in mitigating EMI.In this paper, conducted EMI mitigation is done by applying a spread-spectrum techniques in buck topology LED driver and observing its effect on the LED luminance. Spread spectrum techniques implemented by giving disturbance to the system with 3 profile of waveform signals, filtered square, triangle and sinusoidal waveform signals.
Needs of energy availability for electrical devices is growing high. So there is an effort to produce electrical energy by harvesting energy of electromagnetic waves. Capturing the energy of electromagnetic waves is using a microstrip antenna. Then created a microstrip antenna that standard antenna to capture the energy of the electromagnetic waves. Designed microstrip antenna works at 1920 MHz to 2180 MHz band. In this research designed a microstrip antenna of single rectangular patch type implemented on the system RFEH integrated with power harvester EH300 module. Microstrip antenna is made from materials of 4360 Rogers with dielectric permitivity 6.15 in 1.52 mm. The simulation results are VSWR 1.02, Return Loss -39.93 dB, and gain 3.03 dBi at frequency of 2050 MHz. The test results of implementation are VSWR 1. 166, and gain 2.83 dBi at frequency of 2050 MHz. Output voltage from microstrip antenna implemented in systems of RFEH 12.5 mV in 5 minutes when input power is -46.44 dBm.
Kebutuhan akan perangkat elektronik dengan frekuensi yang tinggi menyebabkan meningkatnya jumlah Electromagnetic Interference (EMI) yang memiliki dua jenis yaitu Conducted Emission dan Radiated Emission. Solusi dari mitigasi EMI tersebut adalah dengan menggunakan filter EMI. Switching Mode Power Supply (SMPS) merupakan sumber daya bagi hampir seluruh perangkat elektronik, namun SMPS ini juga sumber EMI untuk perangkat lain atau bahkan perangkat itu sendiri. Banyak perangkat elektronik yang beredar dipasaran namun belum memenuhi standar EMC. Dalam hal ini mitigasi EMI yang dapat dilakukan adalah dengan menggunakan filter EMI eksternal pasif. Dengan filter pasif ini EMI dari SMPS dapat diredam tanpa memerlukan energi tambahan untuk filter itu sendiri. Penelitian ini akan melakukan perancangan filter EMI untuk meredam noise conducted emission menggunakan sebuah passive EMI filter (PEF) pada SMPS. Filter PEF yang telah dirancang dan diujikan dapat digunakan pada SMPS 1 dan SMPS 2 dengan noise conducted emission sebelum filter sebesar 97,86 dBµV yang diredam menjadi 33 dBµV dan menghasilkan redaman noise conducted emission yang sangat baik (hingga 64,86 dBµV) dan memenuhi standar yang ditetapkan (CISPR22 Class B).
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