Open-ended winding induction machines fed from standard two-level voltage source inverters (VSIs) provide an attractive arrangement for ac drives. An alternative approach is to use a dual-output indirect matrix converter (IMC). It is well known that the IMC provides fully bidirectional power flow operation, with small input size filter requirements. While a standard IMC consists of an ac-dc matrix converter (MC) input stage followed by a single VSI output stage, it is possible to replicate the VSI to produce multiple outputs. In this paper, an open-end winding induction machine fed by an IMC with two output stages is presented. The IMC modulation strategy aims to reduce the common-mode voltage (CMV), while compensating any zero-sequence voltage fed to the machine. The system is modeled using a PSIM and MATLAB/Simulink platform. Experimental results demonstrating the viability of the method are presented using a 7.5-kW prototype.

The development of distributed generation, mainly based on renewable energies, requires the design of control strategies to allow the regulation of electrical variables, such as power, voltage (V), and frequency (f), and the coordination of multiple generation units in microgrids or islanded systems. This paper presents a strategy to control the active and reactive power flow in the Point of Common Connection (PCC) of a renewable generation system operating in islanded mode. Voltage Source Converters (VSCs) are connected between individual generation units and the PCC to control the voltage and frequency. The voltage and frequency reference values are obtained from the P–V and Q–f droop characteristics curves, where P and Q are the active and reactive power supplied to the load, respectively. Proportional–Integral (PI) controllers process the voltage and frequency errors and set the reference currents (in the dq frame) to be imposed by each VSC. Simulation results considering high-power solar and wind generation systems are presented to validate the proposed control strategy.

The research on DC-DC power converters has been a matter of interest for years since this type of converter can be used in a wide range of applications. The main research is focused on increasing the converter voltage gain while obtaining a good efficiency and reliability. Among the different DC-DC converters, the flyback topology is well-known and widely used. In this paper, a novel high efficiency modified step-up DC-DC flyback converter is presented. The converter is based on a N-stages flyback converter with parallel connected inputs and series-connected outputs. The use of a single main diode and output capacitor reduces the number of passive elements and allows for a more economical implementation compared with interleaved flyback topologies. High efficiency is obtained by including an active snubber circuit, which returns the energy stored in the leakage inductance of the flyback transformers back to the input power supply. A 4.7 kW laboratory prototype is implemented considering four flyback stages with an input voltage of 96 V and an output voltage of 590 V, obtaining an efficiency of 95%. The converter operates in discontinuous current mode then facilitating the output voltage controller design. Experimental results are presented and discussed.

This paper presents a methodology for the analytical computation of the slot leakage inductance of tooth-coil winding (TCW) permanent magnet synchronous machines (PMSMs). Generalized equations for the slot leakage inductance of the whole phase are derived, suitable for several slot-pole combinations, and meant to be used during the machine design stage. For simplicity, self- and mutual-inductance components are formulated using the classical method with detailed permeance determination for both horizontal and vertical distribution of coil sides in the slots, considering a straight-line path for the flux leakage. Several slot-pole combinations were simulated by means of Finite Element (FE) method in order to validate the analytical equations, both approaches, FE and analytical, showing adequate concordance.

This paper presents a distributed control scheme for voltage and frequency regulation in a point of common connection (PCC) of a wind farm feeding energy to the grid via an HVDC-Diode Rectifier (HVDC-DR) link. Each wind turbine uses a Permanent Magnet Synchronous Generator (PMSG) with a full back-to-back VSI topology connected between the machine terminals and the PCC. The reference voltage and frequency in each wind turbine is obtained from P/V and Q/f droop characteristics respectively, where Q is the reactive power supplied by each wind energy system an P is the active power obtained from the optimum power wind turbine characteristic. PI controllers process the voltage and frequency errors and set d - q axis reference currents. These currents are imposed at the output of the wind energy systems by fast current control loops. The scheme allows for islanded and grid connected operation. Maximum power transfer from each wind turbines to the PCC is achieved, with good dynamic performance. The strategy has been validated by means of detailed simulations of the system.

This paper analyzes the impact of manufacturing tolerances on the cogging torque of a 24-slot 28-pole tooth-coil-winding permanent magnet synchronous machine with a modular stator core (TCW-MPMSM). Dimensional tolerances and asymmetries associated with the modular topology are studied by means of finite element simulations in order to identify key parameters that increase the cogging torque above the expected values of a faultless machine. Among five selected dimensional parameters, it was found that angular displacement, radial displacement, and tooth–tip width deviations of the stator segments have the most significant impact on the cogging torque. Considering these three key parameters, a full-range tolerance analysis is carried out by means of a proposed superposition-based approach, evaluating all possible combinations of typical deviation values. It is concluded that the cogging torque increment, generated by tolerances, is relatively independent of the faultless tooth–tip width of the stator segments and the arc-to-pole ratio. Robustness of the TCW-MPMSM, regarding cogging torque generation, depends on both the tightness of the tolerances handled in the manufacturing process and the rated cogging torque: the lower the cogging torque of the ideal machine, the less robust is the machine and, therefore, manufacturing imperfections will be required to be tightened.