The droop control strategy, known for its communication-free nature, is widely adopted for the parallel operation of inverter units. However, in microgrids, mismatches in line impedances and various measurement inaccuracies often lead to imbalanced reactive power sharing among inverters and significant circulating current. To address these challenges, this paper proposes an adaptive droop control method that relies solely on local measurements from each inverter, eliminating the need for communication. The proposed approach integrates the deviation between the ratio of reactive power to output voltage and its reference value to generate an Adaptive Virtual Impedance Droop Control (AVIDC) mechanism. This enables a dynamic balance between reactive power output and voltage drop. The simulation and experimental results validate the effectiveness of the proposed control strategy, demonstrating a significant improvement in the accuracy of reactive power sharing.

A novel Halbach permanent magnet array with rectangle section and trapezoid section is proposed and optimized in this paper. The analytical model of the premanent magnet segment is established based on the surface current method, which is numerically efficient and can be utilized to evaluate the magnetic field closely with the premanent magnet segment’s configurations. The analytical model of the Halbach array is acquired based on the superposition principle and coordinate transformation. The fundamental component of the magnetic flux density and the sinusoidal distortion rate are chosen as the optimization object. And the optimization is executed on the Halbach array with one specific set of dimensions by the genetic algorithm in global scale. The effectiveness of the optimization is validated by the finite element analysis. Compared to the traditional Halbach array with rectangle section, the magnetic field created by the optimized proposed Halbach array in this paper owns better performance.

With the rapid development of the industrial sector, the single-inverter power device is increasingly unable to meet the industry’s high-power needs due to the power limitations of semiconductor devices; as a result, parallel connection of multiple devices has become the main means of expanding the capacity of power conversion systems. To address the issues of circulating current and power imbalance caused by discrepancies in the output voltage amplitude and phase among power conversion system (PCS) modules, this paper proposes a master–slave mode-based collaborative control method for energy storage inverters operating in parallel—the method consists of two main components: phase synchronization control and equal amplitude control. The master sends the synchronization signal and voltage amplitude to the slave inverters via the CAN bus, and each slave then adjusts its phase based on the synchronization signal and calculates the modulation ratio of the wave according to their own power supply conditions. This ensures that the output voltage amplitude, phase, and frequency of all slave inverters are fully aligned. Experimental results validate the effectiveness of the proposed parallel coordinated control method, ensuring the stable operation of the parallel system.