Daniel Zammit

MPPT with current control for a PMSG small wind turbine in a grid-connected DC microgrid

This paper presents a Maximum Power Point Tracking (MPPT) system for a small wind turbine (SWT) connected to a DC Microgrid under grid-connection conditions. The system consists of a Permanent Magnet Synchronous Generator (PMSG) driven by a SWT which is interfaced to the DC microgrid through a rectification stage and boost converter. The proposed MPPT system is based on the relationship between the DC link power and voltage, which are used to obtain the required inductor current in the Boost converter to provide maximum power output at all wind speeds. The MPPT system, the Boost converter and current control are explained in detail. Simulation of the system operating under varying wind conditions is presented, showing the performance of the developed MPPT algorithm.

Paralleling of buck converters for DC microgrid operation

This paper presents the controller design of paralleled Buck converters using Droop Control to obtain common load sharing for DC Microgrid operation. Proportional Integral (PI) controllers are used to provide nested current and voltage control of the Buck converters. Droop control is applied to obtain load sharing between the paralleled converters. Then, a voltage restoration loop is applied utilizing another PI controller to restore the desired voltage in the dc microgrid, correcting any voltage deviations caused by the droop loop. The operation of the controllers is tested by simulating two paralleled Buck converters operated in the continuous current mode while sharing a common resistive load.

A MEMS resonator tank for an RF VCO application

This paper presents the design and study of a MEMS tapped-inductor LC resonator tank, proposed to evaluate the improved performance over that generally achieved in standard CMOS passive component integration. The resonator tank, consisting of a fixed-value inductor and a variable capacitor, was implemented in the MetalMUMPs process and was targeted for a VCO intended for telemetry applications. A geometrically optimized 1.25 nH horseshoe inductor was designed and results show that it exhibits a Q-factor of 63 at 7.3 GHz and a self-resonating frequency of 17.6 GHz. In addition, an improved π-inductor model is proposed for design and simulation purposes. The variable capacitor was designed in a parallel-plate topology, using four serpentine springs. The capacitance can be varied from 0.183 pF to 0.245 pF with an actuation voltage in the range of 0 V-to-11.7 V. A Q-factor of 62 at 1.1 GHz and a self-resonating frequency above 10 GHz were achieved. The designed inductor and capacitor were configured in a resonator tank topology yielding an overall Q-factor of 22 at 4.9 GHz.