Ali Djabbari

High-efficiency inverter with H6-type configuration for photovoltaic non-isolated ac module applications

A novel, high-efficiency inverter using MOSFETs for all active switches is presented for photovoltaic, non-isolated, ac module applications. The proposed H6-type configuration features high efficiency over a wide load range, low ground leakage current, no need for split capacitors, and low output ac-current distortion. The detailed power stage operating principles, PWM scheme, and novel bootstrap power supply for the proposed inverter are described. Experimental results of a 300 W hardware prototype show that not only are MOSFET body diode reverse-recovery and ground leakage current issues alleviated in the proposed inverter, but also that 98.3% maximum efficiency and 98.1% European Union efficiency are achieved.

High efficiency converter with charge pump and coupled inductor for wide input photovoltaic AC module applications

Existing photovoltaic (PV) panels have widely varying input voltages based on the panel configuration and size. In this paper, a novel topology with a single active switch — combining boost, flyback, and charge-pump circuits — is proposed in order to achieve wide input range, high voltage gain, high efficiency, and low cost simultaneously. It meets the input-voltage and power-level needs of the majority of modern PV panels while still being suitable for connection with a highvoltage dc bus. The circuit has been designed, simulated, and implemented with the 20 to 70 V input, 200±20 V output, and 220 W output power as a part of a PV ac module. Experimental results verify the validity of the novel circuit and show 97.4% peak efficiency and greater than 96.3% for 50 to 220 W.

High efficiency DC-DC converter with twin-bus for dimmable LED lighting

A novel twin-bus converter using n + 1 active switches is proposed for the n-string LEDs to be dimmable from true zero to the rated current level. With the proposed twin-bus structure, the n-switches that perform the current-loop regulation can operate at very high frequency because of significantly reduced voltage stresses, while achieving high efficiency over a wide load range. With operating frequency exceeding 1 MHz in the test case, the proposed LED driver demonstrates ultra compact size inductor and fast slew rates of the LED current. The dimming controlled switch, however, can operate at a low frequency to ensure high-efficiency operation without light flicker. The detailed power stage operating principle and control scheme of the individual string current for the presented converter are described. Experimental results of a 3-string 50-W LED driver hardware prototype show that the independent string current can be regulated from zero to the desired 350 mA for dimming control. A peak efficiency of 98.3% was achieved with 1.08 MHz switching frequency.

A Power Efficient Modulation Technique for High-Speed Communication over Wired Channels

High speed communication systems play an important role in the development of advanced networks. The optimum design of these communication links under bandwidth and power constraints needs the use of efficient approaches. In this paper, a novel power efficient modulation scheme is introduced. For this purpose, the modulator at the transmitter uses simple and effective pulse shaping functions to change the amplitude and width of the transmitter pulse. Using this simple method, a high power efficient transceiver structure, with the same performance as typical NRZ signaling, can be designed. Our results show that not only we can reduce the power consumption by more than 10\% without loosing the performance but also the probability of error is improved in the presence of jitter and interference.