Isolated converters are the ideal candidate for high-gain DC/DC converter applications. Although the design of converters considers safety margins and derating requirements to ensure acceptable performance until the end of product life, it does not completely rule out any early component failure. It is inevitable that the post-deployment stresses result in component aging and subsequent failure before the end of its useful life. To minimize downtime, early failure signatures need be detected for predictive maintenance, which requires continuous/periodic monitoring of critical components. This paper presents an Extended Kalman Filter (EKF)-based predictive maintenance algorithm of a 2kW, 270V/28V DC/DC converter. The detailed mathematical framework and observability analysis highlighting the feasibility of state/parameter estimation are presented. Based on observability analysis, the converter operating condition is devised such that accurate parameter estimation is achievable at a lower sensor sampling rate (equal to the switching time period). The significance of module-exclusive measurements on the observability and estimation of parameters is also discussed for a two-module system. The analyses presented are validated with detailed simulation results for single (2kW) and double ($2\times 2\text{kW}$) modules to estimate parameters of the filter inductor and the output capacitor.

Unmanned aircraft systems (UAS) have emerged as a useful aid for entertainment, monitoring, and defense activities. A Significant research effort is being invested in UASs to increase the payload capacity and monitoring/processing capabilities. To achieve this, the power density of UAS must be increased. In conventional UAS, for starting the fuel-powered engine, an engine starter is usually used. Once the engine starts, the engine torque is used for driving an alternator, which powers the electrical power system (EPS) of the UAS. This paper presents a novel axial-flux machine-based motor-generator system (MGS), capable to operate as an engine starter thereby eliminating the external starter. The design is targeted to meet the specifications given in the US Army SBIR, to achieve a continuous power density of 3kW/kg for a 7kW power rating. Additionally, the design also meets the dimensional requirements, required to fit with the existing engine. The compact power converter design and control also compliment the motor-generator design. The necessary design steps, and control algorithm to support bidirectional flow are discussed in detail. Finally, detailed simulation results verifying the performance requirement during engine start, generation mode, and emergency mode are also presented.

In the existing power system architecture of military aircraft (such as F-35), electrical loads are fed from two 270V-HVDC buses. These two HVDC buses are completely isolated from each other. In existing architecture, there is no possibility of power transfer between the two buses. This inability reflects as overdesigning of the system to meet the dynamic loads and possible power quality deterioration during operation (occurring due to unequal loading of the two HVDC buses). This paper attempts to address this inability by introducing the concept of dynamic power balancing between the buses. As military aircraft design criteria are sensitive to weight and size, the introduction of the proposed feature must not add additional weight to the system. To ensure this, the authors have studied the existing architecture and have attempted to replace the two 270V to 28V Dual-Active Bridge (DAB) converter (used for charging the 28V battery) with the proposed Triple-Active Bridge (TAB) converter. This converter must be capable of achieving power balancing in addition to the conventional 28V battery charging operation. To achieve this, a modulation strategy to achieve bidirectional power flow and soft-switching is also discussed. Simulation results verifying the feasibility of the proposed converter and control are also presented.

In this paper, three-phase induction motor supplied by multilevel quasi impedance source inverter (qZSI) is controlled with V/f technique. Application of pulse width amplitude modulation (PWAM) technique for controlling the multilevel qZSI is implemented. In PWAM, modulation index which is defined as the ratio of peak of modulating signal to the peak of carrier signal always remains unity. Due to this, the voltage available at the output of the inverter is not controlled in correspondence to V/f control during starting of induction motor. In this paper, a novel control algorithm is proposed which helps in achieving starting of induction motor without starting current transients. Performance of Vlf-controlled induction motor drive obtained with different modulation techniques are compared by simulating the three - phase induction motor drive using Simulink. Comparison of switching losses with these methods is also presented. Experimental prototype of closed loop controlled three - phase seven - level qZSI is developed and tested with RL load.

This paper presents a hybrid method of active power and reactive power control strategy with Quasi Z-source inverter (QZSI) in single phase grid connected photovoltaic (PV) systems. The maximum power from the PV panel is extracted and most of it is supplied as active power to the grid. The major portion of required reactive power exchange to the grid is done by means of thyristor switched capacitor (TSC) and thyristor switched reactor (TSR) to improve the generation capacity of the PV system. In the proposed topology inverter shares the minimum reactive power and large change in reactive power will be delivered/absorbed by the TSC-TSR to get smoother operation in reactive power control. The DC voltage controller and the AC current controller is discussed in brief. The mathematical analysis for grid synchronization method is presented in detail. The control algorithm for active power and reactive power is analyzed and discussed in the paper. The simulation results are shown for validating the proposed concept.