This paper investigated an electromagnetic torque ripple level of BLDC drives with multiple three-phase (TP) permanent magnet (PM) motors for electric vehicles. For this purpose, mathematical models of PM machines of different armature winding sets-single (STP), dual (DTP), triple (TTP), and quadruple (QTP) ones of asymmetrical configuration and optimal angular displacement between winding sets were developed and corresponding computer models in the Matlab/Simulink environment were created. In conducted simulation, the influence of various factors on the electromagnetic torque ripple of the multiple-TP BLDC drives was investigated—degree of modularity, magnetic coupling between armature winding sets, and drive operation in open and closed-loop control systems. Studies have shown an increase of the electromagnetic torque ripple generated by one module in the multiple TP BLDC drives with magnetically coupled winding sets, due to additional current pulsations caused by magnetic interactions between the machine modules. However, the total electromagnetic torque ripples are much lower than in similar drives with magnetically insulated winding sets. Compared with the STP BLDC drive, the multiple TP BLDC drives with the same output parameters showed a reduction of the electromagnetic torque ripple by 27.6% for the DTP, 32.3% for the TTP, and 34.0% for the QTP BLDC drive.

In this paper, dual-rotor counter-rotating (CR) configurations of vertical axis wind turbines (VAWTs) are briefly inspected and divided into three types. This investigation was focused on one of these types—the CR-VAWT with co-axial rotors, in which two equal rotors are placed on the same shaft, displaced from each other along it and rotated in opposite directions. For this CR-VAWT with three-blade H-Darrieus rotors, the properties of the design in terms of aerodynamics, mechanical transmission and electric generator, as well as control system, are analyzed. A new direct-driven dual-rotor permanent magnet synchronous generator was proposed, in which two built-in low-power PM electric machines have been added. They perform two functions—starting-up and overclocking of the rotors to the angular velocity at which the lifting force of the blades is generated, and stabilizing the CR-VAWT work as wind gusts act on the two rotors. Detailed in this paper is the evaluation of the aerodynamic performance of the CR-VAWT via 3D computational fluid dynamics simulations. The evaluation was conducted using the CONVERGE CFD software with the inclusion of the actuator line model for the rotor aerodynamics, which significantly reduces the computational effort. Obtained results show that both rotors, while they rotate in opposite directions, had a positive impact on each other. At the optimal distance between the rotors of 0.3 from a rotor height, the power coefficients of the upper and lower rotors in the CR-VAWT increased, respectively, by 5.5% and 13.3% simultaneously with some increase in their optimal tip-speed ratio compared to the single-rotor VAWT.

In remote locations, it is advisable to combine solar water pumping with electric energy storage and power supply for other forms of consumption. In such complex systems, individual subsystems feature their own local control, and the general automatic control of the system in different modes of its operation is carried out in accordance with an energy management strategy (EMS). In this paper, the functions of local and general control of the solar water pumping system with battery storage and external power supply are combined in the system of passivity-based control (PBC). The EMS is constructed in such a way that for all modes, only two PBC systems are developed, which are switched depending on the battery’s state of charge and the current levels of the two main disturbances—solar irradiation and electrical consumption. For each system, two control influence former (CIF) structures were synthesized and their operation was investigated by computer simulation. Despite the simplicity of CIFs’ implementation, due to the introduced interconnection and damping coefficients, such control allows the provision of the required voltage regulation with a static error up to 1%, sufficient quality of transients during disturbances and switching of the system structure, as well as system asymptotic stability.

In stand-alone photovoltaic (PV) power supply systems, due to daily and weather solar irradiation variability, special devices are used for energy storage, most often batteries. In order to remove stress from batteries during sudden load change, it is advisable to use hybrid energy storage systems (HESS), by adding a supercapacitor module to the battery. In this work, two battery/supercapacitor HESS configurations are investigated - active with two DC-DC converters and semi-active with one DC-DC convertor. Both HESSs are represented as port-controlled Hamiltonian systems, and the synthesis of energy-shaping control systems (ESCS) is carried out using the IDA-PBC method. As a result of the synthesis three structures of ESCSs were obtained. The conducted simulation studies in the Matlab/Simulink environment allowed us to justify the appropriate structures of the ESCSs for each of the HESSs configurations and showed that both systems satisfactorily fulfill management strategy. As a simpler and cheaper, the semi-active battery/supercapacitor HESS can be recommended for use in stand-alone PV installations.

The article presents a comparison by computer simulation the work of dual-rotor vertical axis wind turbine (VAWT) with three types of mechanical transmissions: rigid with the bevel gearbox, semi-rigid with the differential, and soft gearless with the double rotor synchronous generator with permanent magnets. The results of the study have shown the advantages and disadvantages of dual-rotor VAWTs with these transmissions on their start and operation in real conditions that can be characterized by different values WTs moments of inertia and wind gusts at different speeds acting on each of wind turbines (WT). The existence of the backlashes between the gears in rigid and semi-rigid mechanical transmissions causes significant ripples of elastic torques, which are larger in transmission with differential than in gear transmission. This drawback is absent in gearless transmission, making it the most promising to the application in small counter-rotation VAWTs.