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Magnetic nozzles with their contactless feature have opened new grounds for long-distance space travels. For quicker mission completions along with improving system reliability, it becomes necessary to design robust systems that exhibit the ability to confine thrust. A semianalytical numerical method is proposed for rapid and assumption-less calculations of the magnetic field because of a thick coil with rectangular cross section. The method is extended for the proposal of a three-coil setup, where divergence angle of the magnetic field lines is readily controlled in-flight to provide the flexibility to modify the output magnetic thrust and the nozzle’s efficiency. [ABSTRACT FROM AUTHOR]

The increases in number of power semiconductor devices in multilevel inverters increase the probability of fault occurrence and resulting the reduction in the system reliability. The semiconductor switch faults reduce the production quality and with increased duration of fault occurrence may also be the reason for complete system damage. In H-bridge inverters, the fault signatures of diagonally opposite switch fault conditions are approximately similar. Therefore, a fast fault detection with accurate switch identification technique is required. This brief presents a novel fast fault detection with accurate switch identification technique for an H-bridge inverter. The open switch fault with healthy diode is considered for the analysis. The non-ideal characteristics of semiconductor switches are used to identify open switch fault. This brief also proposed a switching time-domain open circuit fault detection technique. The pulse-width modulated inverter (PWMI) output voltage and load current have been used for detection and identification of the switch faults. The level-shifted pulse width modulation (LS-PWM) technique is used for three-level inverter voltage output. [ABSTRACT FROM AUTHOR]

The solar photovoltaic (PV) array generates the power below the rated value due to the shading intensity and shading pattern losses under partial shading conditions (PSCs). The different levels of solar irradiance are received by the modules of PV array under PSCs; it causes the mismatch between the generated module currents, leading unfortunate impacts such as hot-spot and therefore total PV power generation reduces. Resulting, the efficiency of solar PV array decreases. This article presents the optimal energy harvesting using physical relocation and fixed column position of modules with fixed electrical connection (PRFCPM-FEC) under different shading conditions. The proposed algorithm is presented for m × n modules under different shading conditions. The locations of modules are changed according to the proposed configuration without removing the electrical connections. A comparative analysis has also been presented between proposed pattern configuration, total cross tied (TCT), and physical relocation of the modules with a fixed electrical connection (PRM-FEC) configurations. The results demonstrated that the proposed array configuration produced the improved performance under PSCs. [ABSTRACT FROM AUTHOR]

This paper presents a sampled-time-domain analysis to investigate the sampling effect on instantaneous switching frequency of a digitally implemented hysteresis current control (HCC) in a voltage source inverter (VSI). The generalized expression of the instantaneous switching frequency with the consideration of sampling frequency has been derived. The effect of variation in sampling frequency on effective hysteresis band and switching frequency has been analyzed. The difference between maximum to minimum switching frequency of a fixed-band HCC VSI depends on the sampling frequency of the digital controller. The sampling also generates a steady-state tracking error exceeding the fixed-band limit at the fundamental frequency for fixed hysteresis band operation. The analysis has been done to achieve fixed switching frequency with variable hysteresis band and with varying sampling period. The frequency spectrum of the load current is presented to show the effect of a digital controller. The sampling effect on the switching performance has been demonstrated for a single-phase VSI under different loading conditions. To verify the analytical results, the simulation and experimental results are obtained with the current controller implemented on a field programmable gate array-based digital controller. [ABSTRACT FROM PUBLISHER]

This paper characterizes the sampling effect in digital sinusoidal pulse width modulation (SPWM) of voltage source inverter (VSI). The time-domain analysis presented in this paper establishes the relation between the fundamental frequency, carrier frequency, and the sampling frequency at different modulation indices of the SPWM. The analysis investigates the effect of sampling frequency of the digital controller on the output of the VSI. It is shown that the low-frequency harmonic components appear in the frequency spectrum of the VSI output voltage due to sampling. As a result, the output current of digitally controlled VSI is stepped in nature. The double Fourier integral solution of the switched waveform for inner and outer integral limits has been used to derive the expression. The integral solution is obtained using Jacobi-Anger expansions. The generalized results developed in this paper are useful to investigate the sampling effect in high switching frequency DSPWM. The proposed sampling effect has been analyzed for SPWM of single-phase H-bridge inverter. The analytical results are verified using simulation and experimental results. The experimental results have been obtained with the use of field-programmable gate array (FPGA) as a digital controller. [ABSTRACT FROM PUBLISHER]