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In this paper, a topology using a Dual-stator Winding Induction Generator (DWIG) and a boost converter is proposed for the variable speed wind power application. At low rotor speeds, the generator saturation limits the voltage of the DWIG. Using a boost converter, higher DC voltage can be produced while the DWIG operates at Maximum Power Point Tracking (MPPT) even at low speed and low voltage conditions. Semiconductor Excitation Controller (SEC) of the DWIG utilizes Control-Winding Voltage Oriented Control (CWVOC) method to adjust the voltage, considering V/f characteristics. For the proposed topology, the SEC capacity and the excitation capacitor is optimized by analyzing the SEC reactive current considering wind turbine power-speed curve, V/f strategy, and the generator parameters. The method shows that the per-unit capacity of the SEC can be limited to the inverse of DWIG magnetizing reactance per-unit value. The topology is simulated in MATLAB/Simulink platform and experimented with a scaled 1 kW prototype. Both simulation and experimental results demonstrate wide variable speed operation range of the DWIG and verify the optimization.

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THD is the most common criterion to determine the harmonic content of each waveform. Conventional methods, which are usually used, result in approximate answers due to their inability to take all harmonic orders into account. This paper focuses on the three-phase two-level inverter and proposes two methods, founded on the basic definition of THD, to calculate its line voltage THD, precisely. The first method considers stepped essence of line voltage and the second uses its Fourier coefficients. By proposed methods, all harmonic orders of two-level inverter with any switching angles, named n-degree of freedom, are considered. Another feature of the introduced methods is deriving analytical formulas for line voltage THD. This helps some switching strategies like THD Minimisation (THDM) to get rid of heuristic methods, which find those switching angles that globally minimise THD. Superiority of the proposed methods for one and two degrees of freedom is verified by both numeric and graphic results, simulated in MATLAB. The comparison table is only used for higher degrees of freedom, because of impossibility of plotting n-dimensional space. Finally, experimental results for two sets of switching angles are compared with the results of proposed methods to evaluate the accuracy of introduced methods.

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Selective Harmonic Elimination PWM switching strategy has shown tremendous advantages in comparison with well-known SPWM strategy. But, its implementation on Distribution Static Var Compensator (DSTATCOM) is hard because of nonlinear nature of DSTATCOM and severe variation of DC capacitor voltage. In this paper, a controller based on PI controller is designed to overcome such problems. Thus, Modulation Index and phase angle of inverter are used as input control variables to regulate DC capacitor voltage and track reference reactive power. Simulations are worked out in MATLAB/Simulink environment.

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Studies have shown that de¯brillation threshold for current amplitude of biphasic truncated exponential (BTE) waveform has a hyperbolic strengthÀduration relationship. Theoretical and experimental results have shown that decreasing the tilt of BTE waveforms decreases the de¯brillation threshold. On the other hand, low peak current waveform reduces probability of myocardium damage and burn. Therefore, achieving a waveform with low tilt and low peak current is desired. All DC de¯brillators use a capacitor to store and deliver required energy. Because of capacitor discharging nature, the tilt of waveforms is high. In rectilinear biphasic waveform (RBW), which was generated by ZOLL M-series de¯brillator, the tilt of the¯rst phase was decreased using an adjustable resistor connected in series with current path. But the de¯brillator cannot keep the current constant in the second phase and in the both phases for high transthoracic impedances (TTI) either. In this paper, for solving these problems, a circuit that generates rectangular biphasic waveform is designed. In this circuit,¯ve resistors are used and connected in series. Then an IGBT switch is connected to each resistor in parallel. Also, control of minimum current ripple is applied in order to decide which resistors should be worked in each time. The circuit is simulated in MATLAB/Simulink and a prototype model is constructed. Results demonstrate that the tilt of the waveform is notably reduced to a value less than 10%.