In this study, a novel field-oriented control (FOC) algorithm was proposed in a 60° coordinate system for controlling the speed of permanent magnet synchronous motors. The FOC algorithm consists of several parts in which the reference currents and feedback currents are transformed into the representation form in a 60° coordinate system. Current regulators are typically used in a 60° coordinate system to directly obtain the reference voltage vector. The proposed FOC structure was established by incorporating the space vector pulse width modulation algorithm in a 60° coordinate system. The proposed FOC structure simplified the FOC algorithm and reduced its computational burden. The feasibility of the proposed method was verified through simulations and experiments.

In this paper, we consider the gain-phase error calibration problem for uniform linear arrays (ULAs). Based on the adaptive antenna nulling technique, a new gain-phase error pre-calibration method is proposed, requiring only one calibration source with known direction of arrival (DOA). In the proposed method, a ULA with M array elements is divided into $M-1$ sub-arrays, and the gain-phase error of each sub-array can be uniquely extracted one by one. Furthermore, in order to obtain the accurate gain-phase error in each sub-array, we formulate an errors-in-variables (EIV) model and present a weighted total least-squares (WTLS) algorithm by exploiting the structure of the received data on sub-arrays. In addition, the solution to the proposed WTLS algorithm is exactly analyzed in the statistical sense, and the spatial location of the calibration source is also discussed. Simulation results demonstrate the efficiency and feasibility of our proposed method in both large-scale and small-scale ULAs and the superiority to some state-of-the-art gain-phase error calibration approaches.

This paper presents a resonant step‐up DC–DC converter for the photovoltaic micro‐inverter system and describes the converter's operation principle in detail. In the proposed converter, the active‐clamp technique is used to reduce the high voltage spike of the main power switch during its turns‐off. Meanwhile, the output rectifier diodes can operate in the zero‐current‐switching (ZCS) operation and the clamping power switch can operate in zero‐voltage‐switching (ZVS) condition with the series LC resonant circuit. Then, the design procedure for the key components of the proposed DC–DC converter is derived. Finally, experimental prototype with 300 W is established to verify the validity of the proposed topology, and the experimental results shows that the proposed topology processes the merits of few components, simple control, galvanic isolation and high conversion efficiency in a wide photovoltaic voltage input and power range.