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A dual-transformer-based enhanced dual active bridge (DAB) dc–dc converter for wide voltage range applications is introduced in this article. A power leg and transformer of the conventional DAB converter (CDABC) are split in two parts, leading to an expansion of the control freedom. Its wide voltage operating range does not rely on the small leakage inductor design and high transformer turns ratio. The root mean square value of the leakage inductor current is optimized with the ensuring of full domain zero voltage switching. The conduction losses and switching losses can be significantly reduced in buck mode compared to the CDABC. A simple segment control strategy with four control degrees of freedom is employed to avoid inrush from mode switching. The analysis and control processes are simplified, and the control loop is a simple closed voltage loop without the need for look-up table checking. The discussed converter and control strategy are verified by a 1.0 kW prototype. [ABSTRACT FROM AUTHOR]

The concept of the more electric aircraft is aimed at electrifying the mechanical, hydraulic, and pneumatic subsystems on aircraft. With increasing usage of power electronics, the architecture of onboard electrical power distribution systems becomes more complicated. Therefore, it is necessary to analyze the stability of the system. This article, first, presents and validates an impedance model of a permanent magnet synchronous generator as a source and dual active bridge converter as a load. These models are used for the stability analysis of a simple dc power system. In addition, two new control strategies are proposed to enhance the stability of the system. The stabilization effects of the new control strategies are verified with experimental results. [ABSTRACT FROM AUTHOR]

In this article, a low-frequency hybrid modulation technique which is composed of a phase shift-pulsewidth modulation (PS-PWM) and an asymmetric selective harmonic current mitigation-PWM (ASHCM-PWM) are proposed for cascaded multilevel converters to meet the harmonic limit of IEEE 519 2014. In the proposed technique, the harmonics within the concerned frequency range due to PS-PWM are reduced by the ASHCM-PWM so that the cascaded H-bridge (CHB) converter can meet IEEE 519 harmonic limit. The equation set which helps a grid-tied CHB converter meet both harmonic limit and total demand distortion, is developed. The design technique for critical parameters, such as the inductance and the switching frequency of the proposed hybrid modulation technique, is developed. Simulation and experiments are conducted on a single-phase 3-cell 7-level grid-tied CHB converter to validate the proposed technique. [ABSTRACT FROM AUTHOR]

This paper deals with the high accurate current set-points solution for interior permanent-magnet synchronous motors (IPMSM) in wide-speed range applications. Considering voltage and current constraints, the operating regions can be divided into maximum torque per ampere, maximum current, field weakening, and maximum torque per voltage regions, which requires solving different nonlinear functions in real time to obtain optimal current set-points. Traditional methods including curve-fitting methods and polynomial approximation (PA) methods are not easy to obtain these solutions, especially involving magnetic saturation problems. In this paper, Newton–Raphson algorithm for improving the control accuracy of the current set-points is proposed. Meanwhile, parameters influence including magnetic saturation and resistive voltage drop is fully investigated. Compared with PA method, the proposed method is able to converge to accurate solutions in few numbers of iterations with reduced execution time, which can be easily implemented on an off-the-shelf digital signal processor. Both simulation results and experimental results on an 8-kW IPMSM rig are conducted showing good agreement with the expected results. [ABSTRACT FROM AUTHOR]