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Author: search.filters.author.Singh, DheerendraSubject: search.filters.subject.Quasi-Z-source inverter (q-ZSI)

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    Design of an Improved Q-ZSI with Fault Tolerance for EV Applications
    (IEEE, 2019) Bansal, Hari Om; Singh, Dheerendra
    In this paper, a Fault Tolerant Quasi Z-source Inverter (Q-ZSI) topology has been proposed for three phase induction motor drive systems. The proposed topology incorporates the ability to detect an open circuit or a short circuit fault in any of the switching arms. Once a fault is detected the firing signal is transferred to another switching arm to ensure uninterrupted flow of power. The main goal of this paper is to design a rugged inverter topology that can give better performance than the standard Z-Source Inverters (ZSI) in harsh environments where the switches are more prone to faults.
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    Two Modified Z-Source Inverter Topologies - A Solution to the Issues of Start-Up Dc-Link Voltage Overshoot and Source Current Ripple
    (Korea Science, 2019) Bansal, Hari Om; Singh, Dheerendra
    This paper proposes two modified Z-source inverter topologies, namely an embedded L-Z-source inverter (EL-ZSI) and a coupled inductor L-Z source inverter (CL-ZSI). The proposed topologies offer a high voltage gain with a reduced passive component count and reduction in source current ripple when compared to conventional ZSI topologies. Additionally, they prevent overshoot in the dc-link voltage by suppressing heavy inrush currents. This feature reduces the transition time to reach the peak value of the dc-link voltage, and reduces the risk of component failure and overrating due to the inrush current. EL-ZSI and CL-ZSI possess all of the inherent advantages of the conventional L-ZSI topology while eliminating its drawbacks. To verify the effectiveness of the proposed topologies, MATLAB/Simulink models and scaled down laboratory prototypes were constructed. Experiments were performed at a low shoot through duty ratio of 0.1 and a modulation index as high as 0.9 to obtain a peak dc-link voltage of 53 V. This paper demonstrates the superiority of the proposed topologies over conventional ZSI topologies through a detailed comparative analysis. Moreover, experimental results verify that the proposed topologies would be advantageous for renewable energy source applications since they provide voltage gain enhancement, inrush current, dc-link voltage overshoot suppression and a reduction of the peak to peak source current ripple.
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    High voltage gain reduced current ripple switched coupled inductor quasi-Z-source inverter
    (Wiley, 2019-12) Bansal, Hari Om; Singh, Dheerendra
    This article proposes an extended boost switched coupled inductor quasi-Z-source inverter (ESCL-q-ZSI) topology. The key features of ESCL-q-ZSI topology are high voltage gain, ripple-free continuous source current, and common ground between dc source and inverter circuit, and this makes it propitious for PV applications. Due to the presence of two different switched inductor (SL) structures, ESCL-q-ZSI topology offers high voltage gain at low shoot through duty ratio ( Dsh) as compared to reported switched inductor q-ZSI topologies. Low Dsh ensures high modulation index; hence, better output power quality is achieved. Moreover, both the SL structures used in ESCL-q-ZSI topology possess coupled inductors that aid in eliminating ripples in the source current and inductor currents. Thus, the average inductor current, in turn, inductor size required to obtain the same voltage gain gets reduced. This article is initiated with a brief literature review. It summarizes salutary factors in each chronologically developed switched inductor q-ZSI topology and remarks over limitations of each topology. Magnetic and mathematical considerations to design coupled inductor for SL structures are derived. The superiority of ESCL-q-ZSI over conventional topologies is projected through thorough comparative analysis. Effectiveness of the proposed topology is validated through a MATLAB/Simulink platform and a laboratory prototype.
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    Multiple linear regression-based impact analysis of impedance network design on life expectancy of DC-link capacitor in q-ZSI fed motor drive
    (Elsevier, 2021-02) Bansal, Hari Om; Singh, Dheerendra
    Most literature works carrying out capacitor remaining useful life (RUL) prognosis in a three-phase inverter fed Adjustable Speed Drive (ASD) system focus on analyzing the effect of different environmental and operating conditions. But it is the effect of inverter design parameters on capacitor RUL that is of greater interest to the inverter topology designers. This paper performs a parametric investigation on the impact of two design parameters primarily impedance (Z) network inductance (, and shoot through duty ratio ( on capacitor RUL in a quasi-Z-source inverter (q-ZSI) fed ASD system. To perform this analysis, the online condition monitoring (OCM) of a capacitor placed in the Z network of q-ZSI topology is carried out, and its RUL is predicted for varying values of and . The technique/procedure to monitor the operation of the system under study and collect its data for preventive maintenance without interrupting its operation is known as Online Condition Monitoring (OCM). The online method suggested in this paper uses data from the dynamic simulation (DS) model based on non-linear equations of q-ZSI. The use of the DS model increases the accuracy of OCM since it eliminates the use of data collected from sensors that are considered the cause of error in RUL prediction. A dataset of RUL predictions corresponding to multiple combinations of and is obtained through sensitivity analysis using Monte Carlo simulations, and the same dataset is used to derive a Multiple Linear Regression (MLR) model for RUL prediction. The sensitivity analysis data provides inferences on how the change in the selected design parameters affect the capacitor RUL in q-ZSI, and MLR model provides mathematical expression correlating , and capacitor lifetime, with a 95% confidence level. The significance test statistics of the MLR model prove that and are highly significant parameters that impact capacitor RUL in the system under study.