In this paper, a single-switch ultra-high step-up DCDC converter with low voltage stress based on quadratic Y-sources topology is presented. The converter continuous input current makes it suitable for photovoltaic applications. Moreover, unlike many converters based on impedance source networks which suffer from the duty cycle limitations, the duty cycle of the proposed converter is wide. An ultra-high voltage gain with only one switch is achieved in the proposed converter by combining the quadratic boost and the Y-source structures. The usual high switch voltage stress drawback suffered by these structures is significantly reduced by shifting the switch to the low voltage side. A theoretical analysis of the converter is provided and a simulation circuit at input voltage 40V, output voltage 480V and rated power 200W is performed to support the theoretical results. Furthermore, a comparison section explains the advantages and disadvantages among the proposed converter and the counterpart converters.
Reliability is the major concern of megawatt power electronics technology is primarily concerned with reliability, and modular multilevel converter (MMC) is the ideal architecture for various medium-power and high-power applications. This research suggests a hardware-based solution for improving MMC's fault-tolerance. The proposed approach avoids unscheduled interruptions and raises the post-fault line voltage amplitude. This approach achieves maximum balanced line voltages by equalizing the number of functional SMs in the upper and lower legs and adjusting the neutral point location. The suggested strategy is defined for a generic fault situation, and the performance of the proposed method is validated by considering many fault states. The efficiency of the suggested method is shown by simulation results.
Nowadays, ultrasonic systems have many applications in various fields such as welding, cutting, imaging, and cleaning. One of the main requirements of the ultrasonic systems is using a resonant circuit to drive the transducer, properly. In this paper, a high frequency LC resonant inverter is used for driving an ultrasonic cleaner in its optimum frequency, which provides maximum power conversion, as well as optimum clearing performance. Also, zero voltage switching (ZVS) at MOSFETs turn-on times is properly achieved, which reduces the dominant switching losses and electromagnetic interference noise and improves the converter efficiency. Finally, a laboratory prototype circuit has been implemented and tested under different conditions to confirm the performance of the proposed inverter for ultrasonic cleaner systems.
This paper presents a novel configuration of the rotor as a curved rotor switched reluctance motor (CRSRM), which has the weight and volume equal to the traditional switched reluctance motor (SRM). Two considered structures are compared to each other using the 3D finite element method (FEM) and performance validation of novel structure is evaluated by variety in the excitation and speed. The results indicate that CRSRM outperforms the SRM in terms of torque ripple (TR) and radial force (RF). The proposed motor will be a suitable candidate for applications sensitive to the noise and vibration which originates from TR and RF.
In this paper, a method for Zero Crossing Point (ZCP) error correction to improve commutation accuracy, called Index Pulse Comparison (IPC), is proposed. Firstly, Brushless Direct Current (BLDC) motor is mathematically modeled and voltage and torque equations are extracted. Then, the twelve-pulse production strategy, which includes the creation of two types of pulses, is introduced and the time interval between each pulse is calculated. Finally, using the Index Pulse (IP), the deviation time from the ZCP is estimated and the commutation error is corrected. The advantage of the proposed method is the fast correction of ZCP detection error and accurate delay of 30 degrees after ZCP detection to determine commutation instances. The proposed method has been simulated in MATLAB/Simulink environment and its performance has been compared with the ZCP detection error. The simulation result has shown the effectiveness of the proposed method in correcting the ZCP detection error.
