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This paper presents a universal active power filter (UAPF) based on single-phase ac/dc/ac converters with five legs. The proposed topology has multilevel voltage, reduced total harmonic distortion (THD) in current, and low weighted total harmonic distortion (WTHD) in voltage, when compared to conventional four-leg structure. The proposed UAPF is feasible to compensate reactive power, swells in grid...
The modular multilevel converter (MMC) is considered to be the state of the art in medium- and high-voltage application. The nearest level modulation (NLM) method is one of the most popular modulations, however, when applied to MMC with small number of sub-modular (SM), the output waveforms contain large harmonic components. This paper proposes a modified NLM method. By changing the traditional rounding...
The article presents the results of the three-level low voltage inverter circuit topology selection for a high speed electric drive. The main inverter requirements for the high speed application are a high frequency of output voltage, low power losses and low negative impacts in the motor. There are comparable inverters based on fundamental three-level and two-level topologies. The high power switching...
Five-level neutral point clamped H-bridge (NPCH) converter has been found practical application due to its low EMI and high output capacity. However, the unbalanced loss distribution of semiconductor devices in NPCH converter would limit the lifetime and the output capacity. In this paper, a five-level active neutral point clamped H-bridge (ANPCH) converter topology is studied, which is composed two...
This paper proposes a new hybrid asymmetric multilevel inverter for generating the higher number of levels with reduced number of power semiconductor switches. The hybrid asymmetric multilevel inverter consists of full bridge inverter and reduced switch inverter topology. The reduced switch inverter topology can generate 13-level output voltage without utilizing full bridge inverter. When the full...
This paper presents a Multi-Phase Sliding Mode(MPSM) Control Strategy for solving chattering issues inherently existing in DC-DC converters. The main idea of the proposed methodology is to implement a MPSM Control for geometrically nullifying the amplitude of ripple currents yielded by the switching patterns. The benefits of the proposed Multi-Phase Sliding Mode Control strategy involve low-switching...
This paper introduces and generalizes a class of multilevel dynamic voltage restorer (DVR) for voltage sags/swells compensation of high-power sensitive loads. Such a device can improve the power quality of sensitive loads located in stiff systems. The proposed DVR is based on three-phase bridge converters series-connected by means of cascaded transformers using the concept of open-end winding (OEW)...
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, an Optimized Pulse Width Modulation (OPT-PWM) control for a Multilevel Converter (MC) is proposed. The control principle is based on the optimization of the number of commutations. The OPT-PWM control is applied on a five-level H-Bridge Neutral Point Clamped (HB-NPC) converter. First, all of the switching states for all voltage levels are examined. Then, to perform the commutation from...
In a two stage LLC based plug-in electric vehicle (PEV) onboard charger, the dc link voltage is usually kept constant while the battery pack voltage varies in a wide range. This makes it extremely difficult to optimally design the second stage pulse frequency modulated (PFM) LLC resonant converter. In this paper, a modified pulse width modulated (PWM) LLC resonant topology is proposed and investigated...
This paper introduces a high efficiency AC voltage regulator based on an AC/AC buck converter cascaded by a transformer in series with the input voltage. The AC/AC converter uses an overlap time in the gate signals to solve the commutation problem. Non-use of any snubber circuits and current sensors leads to lower cost, smaller size and simpler hardware. The converter generates only the compensation...
Anasymmetric PWM controlled LLCC LED driverwith capacitor connected in series with secondary windingof the transformer is proposed. Due to the presence of the secondary side resonant capacitor, the DC bias of the magnetizing current can be eliminated when asymmetric PWM control is employed. Because the switching frequency is fixed regardless of the load variation, the efficiency of light load is improved...
This paper presents a study of an alternative five level inverter for medium voltage ac drives based on neutral point clamped concepts. The main advantage of this topology is its higher voltage operation compared to the commercial three level structures but with less mounting complexity when it is compared to a traditional five level neutral-point-clamped converters. Besides the converter is suitable...
This paper presents a newly developed 24 V / 3.5 kW output two-stage ac-dc power supply for battery charge application. In this developed two-stage structure, 400 V three-phase three-level T-type PFC ac-dc input stage is followed by an isolated dc-dc buck converter as an output stage. The combination of SiC Schottky Barrier Diodes (SBDs) and Super Junction (SJ) MOSFETs are employed for input stage...
In a hybrid cascaded multilevel converter subject to different DC-link voltage levels among cascaded cells, should conventional carrier phase-shifting pulse-width modulation be applied, it will fail to multiply the equivalent switching frequency of the overall output voltage. As a consequence, this makes it more difficult to design the output filter and limits the overall output bandwidth. Based on...
In this paper a generalized multilevel inverter topology with stacked-coupled-inductors (SCI) is proposed. It is based on two cascaded stages controlled at different switching frequencies and two stacked groups of coupled-inductors. The high-frequency stage is specific to a parallel connection of at least two groups of stacked switching cells, while the low-frequency stage is composed by a basic switching...
For low output voltage application, a half-bridge LLC resonant converter family with synchronous rectifier (SR) that has a boost pulse width modulation (PWM) converter characteristic for hold-up state operation is proposed in this paper. In proposed converters, an auxiliary switch (or an auxiliary switch and a diode) is added at the primary side to provide the charging branch for series resonant inductor...
This paper proposed inverter circuit for low power applications that can generate AC output voltage at fundamental output frequency larger than input voltage without need to increase the number of power switches, several isolated DC source or capacitors and transformer. By applying appropriate duty cycle and PWM switching pattern to the circuit, the near sinusoidal output voltage can be realized with...
In this paper, two-level and three-level voltage source inverters (2/3L-VSIs) with popular pulse width modulation (PWM) methods are investigated in terms of their output (ac-side) voltage and current ripple spectral characteristics and waveform quality properties such as peak-to-peak ripple, rms ripple, and weighted total harmonic distortion. As the switching frequency and the filter size influence...
A modulation strategy for an active rectifier is discussed in this paper. It is designed for an inverter which is structurally based on the topology of the rectifier stage in an indirect matrix converter. This modulation strategy is based on a carrier signal whilst the switching frequency remains variable within a certain range. The switching frequency is dependent on the input value for the inverter...
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