Low‐current ripple LED driver by two‐phase driving approach

ABSTRACT:The design of a voltage source inverter is challenging for PV-grid connected systems due to power quality issues. To improve the power quality,a two-phase interleaved voltage source inverter (IVSI) is proposed in this paper. IVSI phase shifts two voltage source inerters connected in parallel. The inverter topology is interfaced with a 40W PV panel employing a multiple maxima search (MMS) MPPT algorithm. This algorithm results in higher tracking efficiency compared to existing methods. Modelling of the PV with MPPT and the circuit configuration of the interleaved inverter is simulated in MATLAB/SIMULINK. The switches in the IVSI is controlled by employing a unipolar PWM technique. The performance of the IVSI is investigated in terms of weighted total harmonic distortion (WTHD), distortion factor (DF), harmonic spread factor (HSF), and inductor current ripple and compared with classical VSI. From the analysis, it is inferred that the proposed inverter results in reduced total harmonic distortion(THD) and decreased inductor current ripple thereby producing a high-quality output. The hardware model of the two-phase IVSI is developed and interfaced with PV where gating pulses are generated in FPGA. The simulation results are validated experimentally. ABSTRAK: Rekaan pembalik sumber voltan adalah mencabar pada sistem gabungan grid-PV disebabkan isu kualiti tenaga. Bagi memperbaharui kualiti tenaga, pembalik sumber voltan antara lembar dua-fasa (IVSI) telah dicadangkan dalam kajian ini. Anjakan fasa IVSI pembalik sumber voltan dua-fasa telah dihubungkan secara selari. Topologi pembalik telah diantaramukakan dengan 40W panel PV dengan mengunakan carian maksima berganda (MMS) algoritma MPPT. Hasil algoritma menunjukkan lebih tinggi keberkesanan dibandingkan dengan kaedah sedia ada. PV model dengan MPPT dan konfigurasi litar pembalik antaramuka telah disimulasi menggunakan MATLAB/SIMULINK. Suis dalam IVSI dikawal dengan menggunakan teknik PWM unipolar. Dapatan kajian ke atas IVSI adalah berdasarkan berat pengherotan total harmoni (WTHD), faktor pengherotan (DF), faktor sebaran harmoni (HSF), getaran arus pembalik dan dibandingkan dengan kaedah klasik VSI. Analisis menunjukkan kesimpulan dapatan kajian ke atas pembalik yang dicadangkan telah berkurang jumlah pengherotan harmoni (THD) dan getaran arus pembalik telah berkurang, oleh itu menghasilkan hasil akhir yang berkualiti tinggi. Model perkakasan IVSI dua-fasa telah dibangunkan dan diantaramukakan dengan PV di mana signal pengegetan dihasilkan dalam FPGA. Dapatan hasil simulasi telah disahkan secara eksperimen.

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AC–DC Flyback Dimmable LED Driver with Low-Frequency Current Ripple Reduced and Power Dissipation in BJT Linearly Proportional to LED Current

Energies ◽

10.3390/en13164270 ◽

2020 ◽

Vol 13 (16) ◽

pp. 4270

Author(s):

Yeu-Torng Yau ◽

Kuo-Ing Hwu ◽

Kun-Jie Liu

Keyword(s):

Power Dissipation ◽

Light Emitting Diode ◽

Low Frequency ◽

Output Current ◽

Led Driver ◽

Voltage Range ◽

Flyback Converter ◽

Linear Current ◽

Current Ripple ◽

Frequency Current

In this paper, a dimmable light-emitting diode (LED) driver, along with the low-frequency current ripple decreased and the bipolar junction transistor (BJT) power dissipation reduced, is developed. This driver is designed based on a single-stage flyback converter. On the one hand, the low-frequency output current ripple reduction is based on the physical behavior of the linear current regulator. On the other hand, when the voltage across the LED string is decreased/increased due to dimming or temperature, the output voltage of the flyback converter will be automatically regulated down/up, thereby making the power dissipation in the BJT linearly proportional to the LED current. By doing so, not only the power loss in the linear current regulator will be decreased as the LED current is decreased or the LED temperature rises, but also the output current ripple can be reduced. Furthermore, the corresponding power factor (PF) is almost not changed, and the total harmonic distortion (THD) is improved slightly. In addition, the LED dimming is based on voltage division. Eventually, a 30 W LED driver, with an input voltage range from 85 to 295 Vrms and with 24 LEDs in series used as a load, is developed, and accordingly, the feasibility of the proposed LED driver is validated by experimental results.

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