Jianfei Yang

In this paper, a data-driven robust distributed control strategy is proposed for cooperative voltage regulation of the direct-current (DC) microgrids such that the output voltages of all distributed generation units (DGUs) track the specified reference signal. Unlike in decentralized control where all DGUs need to know the information of the reference signal, each DGU only needs to obtain the information of its neighbors in the proposed distributed control strategy. In the presence of the unknown parameters of DGUs, a data-driven robust control method is proposed to achieve cooperative voltage regulation under the available data affected by noise. It is shown that the cooperative voltage regulation problem can be transformed into a local stabilization problem based on the proposed distributed control protocol. To address the local stabilization problem, the noisy data from local DGU and the constructed auxiliary system is collected, and then we develop a data-driven control framework that guarantees robust closed-loop stability under bounded noise. We formulate a data-dependent linear matrix inequality (LMI) based on $ \mathcal{D}_{Q} $-stabilization theory. This LMI enforces all eigenvalues of the closed-loop system to lie within a specified region inside the unit disk, thereby quantifying robustness through guaranteed stability margins when the collected data is corrupted by noise. The resulting gain matrices of the distributed control protocol are computed directly from noisy-data-dependent LMI without requiring any explicit model knowledge. Several simulation results are provided to show the effectiveness and robustness of the proposed methods.

This paper proposes a new separated type permanent magnet (ST-PM) excitation machine (STPMM) based on bidirectional field modulation effect, which has the merits of high quality output torque and high power density. ST-PM can be designed by separating rotor surface-mounted PM into one piece radially excited outer PM and two pieces circumferentially excited inner PMs. This design takes advantage of high airgap flux density, which can be achieved by extending the length and adjusting the rotating angle of inner PMs. The operating principle and design method of the proposed STPMM are provided including the key design parameters. The analytical modeling considering rotating angle of inner PMs in STPMM and bidirectional field modulation effect are presented. The electromagnetic performances of the proposed STPMM are evaluated using finite-element analysis (FEA) and compared with the conventional designs. The FEA-predicted results show that the proposed STPMM exhibits high quality electromagnetic performances. The prototype of the proposed STPMM is manufactured and tested, then, the experimental result confirms the advantages of the new machine topology.

Increasing industrial development puts forward high requirements for the performances of stator permanent magnet (PM) machines, such as torque density and efficiency. The paper proposes a new dual stator PM machine based on field modulation theory (DSPMM), which employs the intermediate rotor participating in the electromechanical energy conversion of the internal and external machine. The proposed machine has the advantages of high torque density and high efficiency and solves the problem of insufficient space utilization of a single stator machine. The evolution process and working principle of the proposed DSPMM are studied. The flux-switching-type PM (FSPM) and the flux-reversal-type PM (FRPM) are employed in the proposed DSPMM, which forms four representative machines. For a fair comparison, the proposed machines employ identical key parameters, i.e., PM volume, the outer radius of the outer stator, and active airgap length. Based on finite element analysis (FEA), the electromagnetic performances of the four representative DSPMM under no-load and rated load, and different copper consumption conditions are analyzed and compared. The calculated results show that the proposed DSPMM with inner FSPM stator and outer FRPM stator can provide high output torque, low torque ripple, high power factor, and high efficiency.

In hydrogen recirculation side channel pumps, the motor rotor is exposed to a high-pressure mixture of steam and hydrogen, which makes hydrogen embrittlement occur in permanent magnets (PMs). A protective coating is necessary for the PMs in high-pressure hydrogen. However, in the process of sleeve interference installation, the protective coating of the PMs is easily damaged. This paper proposes two surface-mounted insert permanent magnet (SIPM) synchronous motor topologies, SIPM1 and SIPM2, in which the retaining sleeves can be eliminated and the PM protective coating is safe in the assembling process. A dovetail PM and rotor core structure is used to protect the PM with higher rotor strength without retaining the sleeve. The electromagnetic performance of the motors with different rotors, including airgap flux density, output torque, torque ripple, and energy efficiency is compared and optimized. It is concluded that the output torque of the SIPM motor can be promoted by 22.4% and torque ripple can be reduced by 2.9%, while the PM volume remains the same as that of the conventional SPM motor. At the same time, the SIPM motor can have lower harmonic contents of back electromotive force (EMF) and rotor loss compared to the SPM motor with a retaining sleeve. Furthermore, the stress of the PM is analyzed under conditions of PM glue action and failure. The proposed SIPM2 has the ability to operate safely at high-speed and high-temperature operating conditions when the PM glue fails.

This paper presents a phase-inductance-based position estimation method for interior permanent magnet synchronous motors (IPMSMs). According to the characteristics of phase induction of IPMSMs, the corresponding relationship of the rotor position and the phase inductance is obtained. In order to eliminate the effect of the zero-sequence component of phase inductance and reduce the rotor position estimation error, the phase inductance difference is employed. With the iterative computation of inductance vectors, the position plane is further subdivided, and the rotor position is extracted by comparing the amplitudes of inductance vectors. To decrease the consumption of computer resources and increase the practicability, a simplified implementation is also investigated. In this method, the rotor position information is achieved easily, with several basic math operations and logical comparisons of phase inductances, without any coordinate transformation or trigonometric function calculation. Based on this position estimation method, the field orientated control (FOC) strategy is established, and the detailed implementation is also provided. A series of experiment results from a prototype demonstrate the correctness and feasibility of the proposed method.

An integrate fabrication framework is presented to build heterogeneous objects (HEO) using digital microdroplets injecting technology and rapid prototyping. The heterogeneous materials part design and manufacturing method in structure and material was used to change the traditional process. The net node method was used for digital modeling that can configure multimaterials in time. The relationship of material, color, and jetting nozzle was built. The main important contributions are to combine the structure, material, and visualization in one process and give the digital model for manufacture. From the given model, it is concluded that the method is effective for HEO. Using microdroplet rapid prototyping and the model given in the paper HEO could be gotten basically. The model could be used in 3D biomanufacturing.