High voltage gain DC-DC converter is a prime requirement for renewable applications, in particular for PV. Though numerous DC-DC converter is available for increasing the voltage gain, the passive elements requirement is higher which reduces the compactness, consequently, increases the cost of the system. To address this issue, a high gain DC-DC converter is reported recently. However, the number of passive elements is quite high which increases the size. To reduce the number of passive elements and maintain the same number of semiconductor devices, in this paper, a new switched inductor arrangement is proposed which is named as switched inductor double switch DC-DC converter (SL-DS-DC). Moreover, the proposed converter has a higher gain as compared to the recently reported converter. The proposed converter is analyzed in steady state and a comparative analysis is presented to prove the suitability. Finally, the proposed converter is validated experimentally.

The essential feature of DC-DC converter for fuel cell vehicle is to ensure the higher voltage gain to meet out the higher DC link voltage demand, continuous input current to improve the life span of fuel cell, presence of common grounding to avoid electromagnetic interference issue and lower voltage stress with reduced components. This paper presents a high voltage gain DC-DC converter by combining the switched capacitor and quasi switched boost networks modules. The proposed high voltage gain converter provides the continuous input current, lower voltage stress, utilizes fewer number of elements and common grounding feature. The operating characteristics, steady state analysis both in continuous current mode (CCM) and discontinuous current mode (DCM), comparative analysis with contemporary converters are discussed. The theoretical claimed analysis is validated by the simulation and experimental study. The proposed converter is operated for 200 W output power rating and tested for providing the voltage gain in the range of 5-8 times the input voltage gain by varying the input voltage from 25 V-40 V. The efficiency of the proposed converter is also reported for different output power rating which is in the range 91.3%-93.7%.

A modular multilevel converter’s (MMC’s) submodule (SM)-capacitor voltage will increase under unbalanced grid conditions. Depending on the imbalance level, the voltage ripple can be considerably high, and it can exceed the pre-defined safe limits. If this occurs, the converter will trip, which can lead to serious stability problems for the grid. This paper first proposes an analytical solution for deriving the three-phase imbalanced SM ripple of an MMC under an unbalanced grid. With this analytical tool, the imbalance mechanism of the SM voltage ripple can be easily understood. What is more, the symmetrical component method is first applied to analyze the three-phase SM capacitor ripple, and the positive-/negative-/zero-sequence components of the three-phase SM voltage ripple are easily identified by the proposed analytical method. Then, based on this powerful analytical tool, the proper circulating-current profile to be injected can be obtained, allowing for the right compensation of the voltage ripple. Based on this approach, two new voltage ripple compensation methods are proposed in this paper. Simulations were carried out to validate the analytical description of the submodule-capacitor voltage ripple proposed in this paper. Moreover, simulation and experimental results are provided to validate the new compensation techniques introduced in this paper.

For high-power and high-performance speed control system, speed feedback signals are generally required. The employment of sensorless control technology makes the installation of the system easier and lower-cost, while its reliability needs to be improved. The robustness of the improved instantaneous reactive power based on the quadrature model reference adaptive system (MRAS) with respect to the variation of the motor inductance parameter is improved by selecting the appropriate reference model and adjustable model. The improved instantaneous reactive power (Q) based on model reference adaptive system (Q-MRAS) algorithm is studied by small signal analysis, and the stability of the control system is verified by the Routh Stability Criterion. The simulation models and experimental platform for the proposed control are built in the laboratory. The feasibility and superiority are verified by the corresponding simulation and experimental results.

In the research of the high-speed sensorless control strategy of an interior permanent-magnet synchronous motor (IPMSM), considering the harmonic influence of inverter nonlinearity on traditional sliding mode observer method, a full-order sliding mode observer (SMO) method based on synchronous frequency tracking filtering is proposed. This method avoids the phase delay defects caused by the use of filters in traditional second-order SMO. Then, the observed extended electromotive force (EMF) signal is filtered using a synchronous frequency tracking (SFT) function. It tracks the changing stator current and filters out harmonics that are not part of the tracking signal to achieve static tracking of the stator current. Then, the rotor speed can be estimated by a Luenberger-based observer. Experimental results verify the effectiveness and feasibility of the proposed method.

This paper presents an integrated power control strategy (IPCS) for a variable frequency speed regulation system, which consists of a back-to-back (BTB) converter and a small film DC-link capacitor. Due to the lack of large-capacity energy storage components in the DC bus, there is a strong power coupling between the rectifier and the inverter. The dynamic response is limited, DC-link voltage oscillates because the traditional method controls rectification and inversion separately. The IPCS is proposed to achieve dynamic balance of the system power through synchronous control of the rectifier and inverter. High conversion efficiency guarantees the power balance of the rectifier and inverter meanwhile reduces the DC bus voltage ripple. To further reduce the DC-link voltage ripple and maintain the stability of the DC-link voltage under step-changes of load, a virtual inertia control (VIC) method is proposed, which consists of a virtual resistance control (VRC) block and a virtual capacitor control (VCC) block. As a result, the DC-link voltage ripple and the total harmonic distortion (THD) of the DC-link current can be improved. Simulations and experimental results are given to provide further validation of the proposed IPCS under different operating scenarios.