Variable DC Load Research Articles

Real-Time Implementation of a Novel Vector Control Strategy for a Self-Excited Asynchronous Generator Driven by a Wind Turbine

This paper proposes a novel idea to governing wind power conversion plants supplying DC loads characterizing an isolated site based on self-excited squirrel-cage induction generators (IG). In this wind power converting application, the induction generator produces an active power from the mechanical power provided by a wind-turbine to variable DC loads through a static converter with an output capacitor under constant voltage levels. For this reason, A specific vector control technique has been developed for controlling the induction machine in an analogous manner with a separated DC machine case. Thus, in order to satisfy the active power demand characterizing a variable DC load at a given rotor mechanical speed, the corresponding control laws are performed in steady-state conditions from a new control variable introduction defined by the ratio of the desired output DC-bus voltage square value and the rotor velocity. Computer simulations validated by experimental results demonstrate that the projected control approach including just one conventional controller ensures excellent tracking performances of the DC-bus voltage to its reference trajectory under simultaneous variations of the load-power demand and the rotor velocity profiles.

Class-E Half-Wave Zero dv/dt Rectifiers for Inductive Power Transfer

This paper analyses and compares candidate zero dv / dt half-wave Class-E rectifier topologies for integration into multi-MHz inductive power transfer (IPT) systems. Furthermore, a hybrid Class-E topology comprising advantageous properties from all existing Class-E half-wave zero dv / dt rectifiers is analyzed for the first time. From the analysis, it is shown that the hybrid Class-E rectifier provides an extra degree of design freedom that enables optimal IPT operation over a wider range of operating conditions. Furthermore, it is shown that by designing both the hybrid and the current-driven rectifiers to operate below resonance provides a low deviation input reactance and inherent output voltage regulation with duty cycle allowing efficient IPT operation over wider dc load range than would otherwise be achieved. A set of case studies demonstrated the following performances: First, for a constant dc load resistance, a receiving end efficiency of 95% was achieved when utilizing the hybrid rectifier, with a tolerance in required input resistance of 2.4% over the tested output power range (50–200 W). Second, for a variable dc load in the range of 100–10%, the hybrid and current-driven rectifiers presented an input reactance deviation less than 2% of the impedance of the magnetizing inductance of the inductive link respectively and receiving end efficiencies greater than 90%. Third, for a constant current in the receiving coil, both the hybrid and the current-driven rectifier achieve inherent output voltage regulation in the order of 3% and 8% of the nominal value, respectively, for a variable dc load range from 100% to 10%.

A Novel Loop Gain-Adjusting Application Using LSB Tuning for Digitally Controlled DC–DC Power Converters

An application was proposed and implemented to digitally adjust the dc loop gain while keeping the loop stability behavior intact in dc converters. This is accomplished by tuning the least significant bit of the digital compensator. This can be done while the converter is in operation and, therefore, a converter with variable dc load line can be obtained. Experimental results verified the validity of the proposed method.

Research into The Future Development of the Hybrid System for Buoy

This paper reports the performance of a 150W PV-wave hybrid system with battery storage in buoy. This system was originally designed to meet a new hybrid power system for buoy in Korea. In the case of lighted buoys and lighthouses, a light failure alarm system of wireless radio is attached so that light failures are immediately notified to the office. At lighthouse offshore fixed lights and light buoys where commercial electricity is not available, the power source depends on solar system and batteries. This power system has a various problems. Therefore energy derived from the sunshine, wind and waves has been used as the energy source for aids to navigation. Recently a hybrid system of combining the solar, wind and the wave generator is a favorable system for the ocean facilities like lighthouse and buoy. The hybrid system in this paper is intended for variable DC load like light, communication system in the buoy and includes a PV-wave generation system and battery. This is composed a high efficiency charging algorithm, switching converter and controller. This paper includes discussion on system reliability, power quality, and effects of hybrid system in the buoy. Simulation and experimental results show excellent performance.