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Ultra-high speed machines have become more and more interesting to researchers in the past few decades. Switched reluctance machines (SRMs) are very attractive to researchers due to their simple geometry. However, traditional control methods are not suitable for ultra-high speed applications because of their super-high switching frequency. In this paper, a constant volts per hertz control for ultra-high...
SiC devices are now achieving voltage and current ratings which challenge applications previously dominated by IGBTs. Unlike with IGBTs parallel connection of SiC devices may be used to reduce conduction losses. SiC conduction loss is reduced with low Rds(on), or large die area, while switching loss reduction requires small Coss, and small die area. An improved analytical model is presented to accurately...
Power semiconductor devices made with wide-bandgap (WBG) materials such as Silicon Carbide (SiC) are improving the energy conversion efficiency, power density, and switching performance of converters. This paper presents a comparative performance evaluation of Si IGBT, SiC JFET, and SiC MOSFET power devices implemented in an otherwise identical, non-isolated dc-dc boost converter. Switching characteristics...
This paper presents a novel semiconductor switch test platform for power converter optimization which allows to test power semiconductors under different switching current waveforms. As switching current has a major influence on the switching behavior of power semiconductors and thus on switching losses. Compared with conventional double pulse test circuit which can only test power semiconductors...
Due to the limitations in the operating conditions of the conventional silicon (Si) power device based dc-dc buck converters as well as its notable power losses, there is an increased interest and need to exploit the promising features of wide bandgap power devices toward more efficient converters. This paper presents the design of an efficient, high performance and reliable non-isolated dc-dc buck...
This paper presents a novel variable switching frequency PWM method for torque ripple control of three-phase AC motors. First, the switching torque ripple model is analyzed through the PWM current ripple in the motor. Based on the switching torque ripple prediction model, variable switching frequency PWM is developed to control the torque ripple maximum value. With this method, the switching losses...
This paper discusses suitable short-through mode for a Z-source inverter using SiC-MOSFET to achieve high switching frequency operation. The Z-source inverter has short-through mode for boost operation and several control techniques about short-through mode have been discussed from points of device stress and boost ratio; however, loss analysis from perspective of short-through mode implementation...
Multilevel converters (MCs) are utilized in medium voltage (MV) high power applications due to its higher efficiency than two level converters. On the other hand, modular multilevel converters (MMCs) provide several advantages with regard to other MCs, such as higher scalability, reliability and no requirement of a common DC capacitor. Particularly, low switching frequency modulations, such as (2N+1)...
This paper deals with a new control system based on finite control set model predictive control designed for a dual voltage source inverter. The proposed control systems deals with three objectives, the first one is the output current control depending on the load current demands, the second part of the control system is balancing of power losses among the semiconductor devices using redundant switching...
Thanks to scalability, performance and efficiency, the Modular Multilevel Converter (MMC), since its invention, becomes an attractive topology in industrial applications such as high voltage direct current (HVDC) transmission system. To control such device, the Balancing Control Algorithm (BCA) for submodule capacitors is a key issue. Lots of papers have been written in this field, but most of them...
The average switching frequency of the Modular Multilevel Converter (MMC) is a characteristic system parameter, which affects the losses of the converter system. Several investigations were done to reduce the switching frequency by applying different modulation strategies. Up to now the switching frequency is always an indirect and random outcome of the modulator and it is not directly controlled...
The switching frequency at which the inverter operates is an important parameter that significantly affects the operation of the inverter. In this paper, a new variable switching frequency algorithm is proposed in which the switching frequency is varied in response to the variation in the operating conditions. The proposed algorithm is based on multi-objective optimization problem formulation such...
Multilevel inverter units for stand-alone solar photovoltaic systems are gaining popularity in the present industrial environment. The number of switching devices, total harmonic distortion, number of output levels and number of sources are the governing factors in a multilevel inverter topology. The classical multilevel inverter topologies produce a considerable amount of switching losses due to...
In this paper, a Three level NPC four leg inverter is used as a shunt active power filter (SAPF), and the Three level Three Dimensional Space Vector Modulation technique in the aßo axes (3-level 3D SVM) for generate the switching signals of this SAPF for power quality improvements under balanced and unbalanced loads are proposed. In order to, improved the output voltage forms, lower switching losses,...
In this paper, a new operation strategy for switched capacitor converters is presented. This operation mode increases the converter efficiency throughout all the load range, including heavy and light load conditions. The efficiency is increased by adjusting the switching frequency, based on the analysis of the power loss model. In order to support this concept, theoretical analysis and experimental...
Soft magnetic composite (SMC) is considered as an alternative solution for core materials of inductors used in LCL filters in power converter applications. Performance of SMC inductors in damping a range of harmonics caused by voltage switching is an interesting topic. The method used in this paper is to test the inductors together with a 70 kW PWM inverter to examine the filtering effects for different...
This paper shows modified PWM algorithm for control of the series resonant converter working with the low duty cycle in comparison with standard PWM. Proposed algorithm is used in combination with standard PWM to achieve lowest switching losses in whole output voltage range. The standard algorithm uses basic pulse-width modulation with pulses centered to the waveforms of current. That is disadvantageous,...
The application of voltage source multilevel inverters, in medium voltage-high power applications, is growing enormously. These inverters generate a near sinusoidal staircase output voltage waveform. Key attractions of multilevel inverters, compared to conventional two level inverters, are: higher output voltage can be achieved at low switching frequency, low voltage stress(dv/dt), lower total harmonic...
The utilization of multi-cell converters, through the use of low voltage semiconductors, has permitted to implement medium and high voltage applications as PV farms and AC drives. In conventional AC drives, this converter requires an input multipulse transformer, which allows the low frequency harmonic cancellation that are generated by the three-phase diode rectifiers included in each cell. This...
LLC resonant converter is an attractive topology to achieve high power density with high efficiency. However, the high switching frequency and circulating current result the poor efficiency of a LLC resonant converter under light load condition. To improve efficiency further, a modified burst-mode control is implemented in the proposed controller. The switching frequency decreases gradually during...
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