Design and Implementation of Z-Source Inverter by Simple Boost Control Technique for Laboratory Scale Micro-Hydro Power Plant Application

In a power plant such as micro-hydropower (MHP), an induction generator (IG) is usually employed to produce electrical power. Therefore, an inverter is needed to deliver it with high efficiency. Z-source inverter (ZSI) has been introduced as a topology with many advantages over conventional inverters. This research aims to investigate the performance of ZSI based simple boost control (SBC) in laboratory-scale MHP systems using a rewinding induction generator. This research has been conducted both from simulations and experiments. Based on the result, the waveform characteristic and value of ZSI are close to the desired design. A shoot-through duty ratio of 17% can reach 60 Vrms output voltage, and this condition has a conversion ratio of about 2.05 times. Also, SBC can significantly reduce the Total Harmonic Distortion (THD). ZSI efficiency has a value of 84.78% at 50% of rating load 100 W and an average value of 80%. Compared to the previous study, the proposed design has more economical with the same component for the higher rating power. Moreover, it has a smoother and entire output waveform of the voltage.

Analysis of Multi-Phase qZ-Source Inverter with Maximum Constant Boost Control Technique

This paper proposes a topology of two-level qZ- source multiphase inverter based on maximum constant boost control algorithm which can be used to power multiphase machines. Indeed, these kinds of machines have many advantages compared to their counterpart three-phase machines, which are actually used extensively in many industries. On the other side, the qZ-source inverter has also many advantages compared to the conventional inverters, mainly high boosting capability, more freedom degrees of switching states and less voltage and current stresses of switches can be obtained. Such advantages among others make it to be a good candidate in many industrial applications. Thus, the present paper proposes the topology of two level five-phase qZ-source inverter, where the main aim is to be used for driving the five-phase machine and consequently benefiting from the merits of the advantages of both topologies of the machine and the inverter in building one combined topology. The simulations results obtained in this paper prove the quality of the improved performances of the proposed topology in comparison with previous works which can be a promising solution in many industrial applications based on the afore mentioned advantages.

Sinusoidal PWM techniques comparison for the Quasi-Y-Source Inverter

Impedance networks inverters (INI) have emerged as an alternative to improve traditional inverters, allowing their operation as a buck-boost type converter, through the utilization of the "shoot-through" conduction state, where switches of one or more inverter legs are gated on simultaneously. Recently introduced, the Quasi-Y-Source inverter (QYSI) is a magnetic coupled INI that has particular performance advantages, specially for renewable sources and distributed generation. To control the QYSI there is several techniques based on Sinusoidal Pulse Width Modulation (SPWM), that are modified to allow the shootthrough state. This work aims to present, through computational simulations, a comparative analysis of three SPWM techniques applied in three-phase QYSI, considering a fixed boost factor and a three-phase/three-wire RL load connected to the inverter output. The following modulation techniques were compared: Simple Boost Control (SBC), Maximum Boost Control with third harmonic injection (MBC3h) and Maximum Constant Boost Control with third harmonic injection (MCBC3h). Simulation results show operation characteristics of the QYSI for the different modulation techniques. A Fourier analysis was performed in order to evaluate harmonic distortion and harmonic spectrum for both inverter output voltage and current, and a comparative analysis was performed showing several relationships among voltage gain, switch voltage stress, shoot-through duty ratio and modulation index for the different SPWM techniques. Simulation results shows the advantages and disadvantages of each SPWM technique applied to QYSI and the impact of the coupled inductor on inverter performance, helping to establish proper criteria for choosing among SPWM techniques for different power systems applications.

Lyapunov-Function-Based Controller for Single-Phase NPC Quasi-Z-Source Inverter with 2ω Frequency Ripple Suppression

This paper proposes a high-performance control technique based on Lyapunov’s stability theory for a single-phase grid-connected neutral-point-clamped quasi-impedance source inverter with LCL filter. The Lyapunov function based control is employed to regulate the inverter output current, whereas the proportional resonant controller is used to produce the reference of the inverter output current that is needed in the Lyapunov function based control. Use of proportional resonant controller ensures the zero steady-state error in the grid current. An important feature of the proposed Lyapunov function based control is the achievement of resonance damping without using a dedicated damping method. Furthermore, the modified simple boost control technique is proposed to eliminate the double-line frequency ripples in the quasi-impedance source inductor currents and minimize the double-line frequency ripples in the quasi-impedance source capacitor voltages. The proposed control technique considerably reduces the inverter size, weight, and cost as well as increases overall system efficiency since the required inductances and capacitances sizes are lower. Experimental results obtained from a 2.5 kW neutral-point-clamped quasi-impedance source inverter prototype are presented to validate the performance of the Lyapunov function based control technique.

Tehran will step up US confrontation to boost control

Headline IRAN: More US confrontation will boost regime control