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Harmonic suppression plays a key role in the current control of dual-three-phase (DTP) permanent magnet synchronous machines (PMSMs). Existing current control schemes are scarcely verified by designed DTP motor prototypes or consider the impact of inherent electromotive force (EMF) harmonics quantitatively. Also, few studies discuss the low-reactance case which requires additional concerns for current prediction and modulation. Therefore, this article conceives and presents an improved deadbeat-based active current harmonic control scheme particularly for low-reactance PMSMs. From the aspect of motor design and finite element analysis, the quantitative effect of EMF harmonics on control behaviors is analyzed. Based on the non-ideal mathematical model (MMM) of designed slotless PMSM with analyzed EMF harmonics, the proposed scheme is firstly introduced theoretically and verified by simulation. Subsequently, the slotless PMSM prototype fabrication and control experiments validate the proposed scheme and recognize the necessity of active harmonic suppression.

This article presents a high-fidelity analytical solution and a fast integrated optimization method for vernier machines. First, a harmonic modeling method (HMM) is adopted to obtain the magnetic field distribution of vernier machines. Particularly, the stator teeth of vernier machines are divided into several blocks to take account of the local magnetic saturation of soft-magnetic material. Then, the electromagnetic parameters, such as the average torque, torque ripple, and efficiency, can be calculated via the analytical model. Next, the proposed harmonic model is combined with the nondominated sorting genetic algorithm II (NSGA-II) to determine a multiobjective optimal design for the studied vernier machine. This integrated optimization method can save computation time, because the data interaction process between the finite-element analysis (FEA) software and the optimization software is eliminated. Finally, the performances of the optimal case are verified by both FEA and experiments with the prototype.

Unprecise voltage vectors applied in conventional model predictive control (MPC) would cause additional ripples in electromagnetic torque. To eliminate the problem, this article proposes an improved model predictive torque control (MPTC) based on deadbeat solution and discrete space-vector modulation (DSVM) for dual three-phase permanent magnet synchronous machines (PMSMs). First, deadbeat-direct torque and flux control (DB-DTFC) algorithm is applied and simplified, so that the computational burden can be reduced. Second, the virtual voltage vectors (VVVs) are adopted in dual three-phase voltage vector space to reduce voltage harmonics. Also, the DSVM is further proposed in this VVVs based vector space to generate more voltage vectors. After that, the simplified DB-DTFC and the DSVM scheme are artfully combined to select suitable voltage vector candidates for the MPTC, and the best one is then chosen to control the dual three-phase PMSMs. Finally, both simulation and experimental results are given to verify the effectiveness of the proposed method.

To explore the applicability of HEC-HMS and its parameter regionalization in small ungauged watersheds in hilly areas, this paper takes hydrological divisions III and IV of Henan Province as the research area. The HEC-HMS model is applied to three typical small watersheds in Luanchuan, Gaocheng and Xiahecun. On the basis of verifying the validity of the model, the regression relationships between model parameters and underlying surface characteristics are established and verified in the Zhongtang small watershed. The results show that the qualified rates of runoff depth, flood peak flow, peak occurrence time and NSE in flood simulation are higher than 75%, and the accuracy reaches the grade B level regardless of the HEC-HMS model test or the parameter regionalization method verification. In summary, the HEC-HMS model can be applied to simulate the rainfall-runoff process of small watersheds in hilly areas, and the parameter regionalization method can effectively deduce the model parameters of HEC-HMS for small ungauged watersheds in hilly areas.

In permanent-magnet synchronous motor (PMSM), the winding current consists of different orders of harmonics due to the manufacture error, deadtime, and disturbances. This article proposes a winding current harmonic suppression method for PMSM by reducing the dominant fifth- and seventh-order current ripples. First, with reference frame transformation, the fifth- and seventh-order current ripples convert to sixth-order ripples in the synchronous reference frame (SRF). Then, with further transformation, these sixth-order ripples turn to dc signals. Next, the type-II Chebyshev filter is designed to extract these dc signals. Also, the proportional–integral (PI) controller is adopted to generate the current harmonic control voltage, which is setting the dc current harmonic signals reference to be zero. Finally, the current harmonic control voltage is compensated to the voltage reference in the SRF. Both the simulation and experimental results are presented to verify the effectiveness of the proposed method.

In this article, a new double-rotor multiwinding machine (DRMWM) that utilizes the flux modulation principle is proposed for propulsion system of hybrid electric aircrafts (HEAs). First, the operation principle of DRMWMs and the corresponding HEA propulsion configuration are introduced, where different operation modes of two rotors and three sets of windings of DRMWMs to cope with various flight tasks of HEAs are elucidated. Then, an improved subdomain method is utilized to solve the magnetic field distribution of DRMWMs with the consideration of saturation effect of soft-magnetic material (SMM). Finally, a prototype is manufactured to verify the effectiveness of the proposed improved subdomain method in predicting the electromagnetic performances of DRMWMs. The experiment shows that the DRMWM is a good candidate to be applied in HEA with different operation modes.

This paper proposes a new five-phase dual-stator consequent-pole brushless hybrid excitation machine based on rotor permanent magnet (rotor-PM) for wide-speed range and high output torque application in electric vehicles (EVs). To achieve brushless hybrid excitation, this machine integrates the advantages of rotor-PM and electricity excitation, in which dual stator is adopted. The key is the consequent pole, which can construct several mutually uncoupled magnetic circuits to achieve hybrid excitation. In the proposed machine, the volume of PM is decreased but the similar output torque capability is achieved, and the flux can be regulated by excitation windings effectively. The topology and operating principle of the proposed machine are analyzed. The electromagnetic properties such as the torque waveform, the back electromotive force, and the flux-regulating capability are all investigated by using finite-element analysis. Then, the machine parameters are optimized and studied. For better heat dissipation, the mechanical design is proposed. Finally, a prototype is built; the agreement of the experimental results and the simulations shows the proposed machine can provide with high output torque, high space utilization, and good flux-regulating ability in the applications of EVs.

This paper presents a new nonlinear algorithm of speed regulation system for a flux-modulated permanent magnet in-wheel (FMPMW) motor. To improve the robustness and static performance of speed regulation system, sliding mode control with a sigmoid function is adopted. Compared with PI controller, the proposed algorithm can improve the robustness and minimize the torque ripple of the system. In addition, an adaptive notch filter is proposed to restrain the fifth and seventh current harmonics, which the static performance of control system can be further improved. Based on a 2-kW FMPMW prototype motor, the simulation and experimental results verify the good robustness and static performance of the proposed algorithm.

In this article, a new dual-modulator magnetic-geared machine (DM-MGM) is proposed for tidal-power generation with the virtue of high-torque output at low speed. First, the requirement of the DM-MGM for tidal-power generation is derived. Then, the flux-modulation principle and flux-enhancing effect of the extra modulator of the proposed DM-MGM are elaborated. After that, a finite-element analysis and multi-objective genetic algorithm (FEA-GA) combined method is used to solve a multi-objective optimization problem for the DM-MGM design. The electromagnetic performances of the optimized DM-MGM with different pole-pair combinations are quantitatively compared by FEA. The results show the effectiveness of the proposed machine, which is suitable to be applied in the tidal-power-generation scenario.

This paper presents a new speed control system for a flux-modulated permanent-magnet (FMPM) in-wheel motor. It is based on deadbeat-direct torque and flux control (DB-DTFC) to reduce the torque ripple and improve the steady performance compared with conventional SVPWM-DTC system. DB-DTFC calculates the control input of next control period so that a new stator current observer is proposed to predict the stator current in next control period. Simulation is built up to verify the accuracy of the current observer and to validate the system performance. Then, experiments of the observer and the DB-DTFC system is implemented based on a 2-kW prototype motor. The results demonstrate the advantages of the DB-DTFC system.

This paper describes a simple and effective way to modify an existing hard-switched flyback power converter into a circuit with zero-voltage switching (ZVS) and zero-current switching (ZCS). The key improvement is to turn the unattractive features of the coupled inductor leakage inductance and snubber capacitor into attractive ones. The coupled inductor leakage inductance and snubber are used to form a quasi-resonant circuit to facilitate ZVS/ZCS of all power devices. The operating principles of the power converter and experimental results are presented.