This article presents an accurate method to determine the mandatory rotor position to control a permanent magnet synchronous machine from misplaced Hall-effect switch sensors. The main feature of this technique is the estimated speed from two consecutive edge transitions in the same phase to dodge the inaccurate information. Besides, when a new electrical cycle starts, a gradual compensation algorithm corrects the initial speed estimation to cancel the electrical angle error in order to prevent current distortions. Furthermore, a first-order Taylor series approximation estimates the rotor position from the compensated speed calculation, reducing the possible torque ripple and noise due to an inaccurate control strategy. The proposed method has been compared with other state-of-the-art approaches through simulation and experimental results obtained from a low-voltage powertrain, showing more straightforward implementation and delivering the best balance performance during steady-state and transient operation.

Anti-islanding detection methods have been part of a secure operation for distributed energy resource inverters, avoiding the creation of non-intentional energization when the mains are lost. These detection mechanisms were conceived historically for current-controlled inverters. New control possibilities have broken ground, and current- or voltage-controlled inverters are a reality; however, special attention must be paid to detection strategies when applied to the latter ones. This paper addresses two topics: it exposes the lack of effectiveness of those detection algorithms based on the voltage/frequency displacement concept under voltage-controlled inverters and evaluates the applicability limits of the others based on the impedance measurement (IM). The IM is presented as a valid mechanism to achieve the islanding detection, but the exploration of its limits drives the concept of detection frequency bandwidth (DFBW), introduced in this paper. The DFBW is suggested as a practical approach to select the proper injection frequency to measure. Therefore, an improved strategy based on the IM and DFBW is proposed to allow achieving the detection towards (non-)resonant loads considering low computational burden. The results were experimentally validated in a 90-kVA four-wire voltage-controlled inverter, offering detection times of less than 100 ms in any case.

This paper proposes a novel Space Vector Pulse Width Modulation strategy extending conventional 2-D SVPWM strategies for its use in three-phase four-leg inverters. The methodology is based on the segregation of the zero sequence from any initial desired unbalance voltage set-points. In this way, the operation of the fourth leg is reserved to manage the desired homopolar component and to compensate for the inherent homopolar component provided by any 2-D SVPWM technique. This choice not only minimizes the complexity and effort to determine the location of the reference voltage space vector from a 3-D to a 2-D space but also enables to use 75% of the affordable space to synthesize voltages under a 3-D SVPWM technique. Furthermore, the proposal is compared with other four 3-D SVPWM techniques analysing the advantages in terms of execution time, memory program, simplicity and neutral to mid-point voltage quality, resulting into a really good implementing alternative compared with the major 3-D SPVWM techniques analysed. The new modulation strategy is presented in detail, and a complete set of simulations using this particular modulation strategy has been done, and the results of these simulations have been validated on a laboratory set-up using a four-leg inverter.

This paper proposes a triangular modulation with zero current switching (ZCS) for a hybrid Si-SiC isolated bidirectional DC-DC converter (IBDC). Three of the four legs in the IBDC operate at ZCS and use Si IGBTs, while the fourth operates at zero voltage switching (ZVS) and uses SiC MOSFET. In that case, the turn-off switching losses are concentrated regardless of the direction of the power. The main contribution of this paper resides in the proposed dead-band compensation mechanism. This dead-band compensation is crucial when addressing ZCS modulation and improves the overall efficiency of the full operating range. As a co-benefit, the proposed mix of semiconductor technologies can result in an effective cost reduction compared with a full SiC IBDC. The paper contains a detailed explanation of the implemented modulation applied to an IBDC. The paper contributes to deploy a theoretical implementation where the effect of parasitic capacitance on semiconductors during the dead-band is analytically considered. The presented method results are validated on a laboratory set-up using a 20 kW - 40 kHz hybrid Si-SiC IBDC.