In this article, a new low-cost direct DC-link current control (DDLCC) is proposed for the brushless direct current motors. The newly proposed DDLCC method has a fast dynamic torque response analogous to the direct torque control (DTC) method. Additionally, torque ripple reduction between two consequent commutations, the standstill and low-speed operation, the low-cost drive, and the reliability enhancement are provided by the proposed DDLCC method compared with the DTC method. Transferring the motor variables to the stationary or synchronous reference frame, which leads to having a high computational burden, is not required in this method. A simple derivative-based (SDB) method is proposed as well to provide the torque ripple without its dc offset value. The commutation interval is easily detected by a two-level hysteresis controller, and the commutation torque ripple is suppressed by applying the appropriate voltage vectors. Both the DDLCC and SDB methods are analyzed and then compared with some of the available DTC methods. Finally, the validity and performance of all analyzed methods are appraised by simulation and experimental results.

This paper focuses on the efficiency improvement of the cascade buck converter (CBC). By changing the position of the second stage inductor, the output current is shared between both the first and second stage inductors and as a result, the total volume of the magnetic components and their conduction losses are decreased. Besides, by proper design of the inductors, the frequency of the output current ripple will increase to twice the conventional CBC with a lower p-p amplitude which results in a further decrease in the size of passive components. The proposed improved CBC is analyzed, and its operating principles are presented. The theoretical analysis is verified by the experimental results of a 400V input and 24V120W output prototype converter.

In this study, a novel two-stage grid-tied high step-up inverter is proposed. The first stage (DC-DC) is a combination of boost and cuk converters as well as a simple DC-link voltage balancing circuit. The balancing circuit is connected in series with the output of the cuk converter to compensate for the output voltage difference between boost and cuk converters. The second stage (DC-AC) comprises a conventional half-bridge inverter. The ground leakage current is eliminated in the proposed topology by the simultaneous grounding of the PV module and the grid. A lossless passive snubber with the minimum elements is also proposed and analyzed to provide the soft-switching conditions. In this snubber circuit, the snubber capacitance discharges to the output DC-link to decrease the converter circulation losses. The main attributes of the proposed DC-DC converter with lossless passive snubber are the simple structure of the DC-DC converter and snubber circuit, simple control scheme, and high efficiency. Various operation modes of the proposed topology are theoretically analyzed and investigated. The experimental results substantiate the effectiveness and performance of the proposed boost-cuk-based high step-up inverter with the lossless snubber.

In this study, a novel fully soft-switched high step-up dc–dc converter is proposed. The proposed converter comprises the integration of boost and Ćuk converters with the same input inductor and mosfet and series-connected output dc-link voltages. In this topology, the switch is turned-on under zero current switching (ZCS) and low-voltage conditions since the converter works under discontinuous conduction mode due to small output Ćuk inductance. In addition, two coupled inductors are applied to create a similar voltage gain and soft switching conditions for all semiconductor elements. The first coupled inductor is placed in series with the Ćuk diode, which provides a balanced dc link for wide load and input voltage variations and ZCS conditions for the Ćuk diode. The second coupled inductor forms a lossless passive snubber to provide a zero-voltage switching turn-off condition for the main switch. This lossless passive snubber provides a clamped circuit and reduces the turn-off slew rate of the switch voltage. This snubber circuit is simple with minimum elements, and the snubber capacitor discharges to the output while the switch is off. Moreover, the input current is ripple-free, which is appropriate for renewable energy systems integration. The experiments substantiate the effectiveness of the proposed converter.

This study presents a combined vector and direct torque control (CVDTC) for surface‐mounted permanent magnet synchronous motor (SM‐PMSM). The CVDTC method has a fast dynamic torque response without requiring any conventional PWM signal‐generators. Besides, it provides low‐speed control and standstill operation, torque and flux ripple reduction, minor switching frequency variations, and low computational burden. In this study, CVDTC is mathematically analysed in the stator flux reference frame and then both DTC and CVDTC are simulated and compared for SM‐PMSMs. To further reduce torque and flux ripple, model predictive combined vector and direct torque control (MPCVDTC) with the finite control set is analysed and proposed in the stator flux reference frame. Moreover, maximum torque per ampere (MTPA) and constant stator flux magnitude analysis for SM‐PMSM are explored in the stator flux reference frame. Simulation and experimental results substantiate the effectiveness and performance of the CVDTC and MPCVDTC methods over a vast speed range.

This paper introduces a novel dual-air-gap surface permanent magnet synchronous motor (DAG-SPMSM) and investigates its electromagnetic characteristics. The motor comprises two stators (inner and outer) and a single rotor with permanent magnets on both sides (inner and outer). The magnets are arranged in a zig-zag configuration to isolate the inner and outer stator and rotor magnets. Additionally, a magnetic shield is incorporated into the rotor to further isolate the rotor magnetic flux, which results in a localized short flux path that can reduce core loss. The insertion of the magnetic shield also affects the flux path, reducing torque ripple. The electromagnetic characteristics, such as flux path, flux density, and torque, are analyzed using finite element analysis. The effectiveness of using a magnetic screen is also evaluated, and simple experiments are conducted to validate the observed characteristics of the proposed motor.