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This paper presents discontinuous pulse width modulation (DPWM) scheme for a modular multilevel converter (MMC) to achieve an advanced switching losses reduction. The MMC is considered to be one of the most attractive multilevel topology for high-power applications because of the features of its high power quality, modularity, and availability. However, the MMC has large switching losses because of...
This paper discusses reduction of capacitances of dc capacitors in the previously proposed smart charger (SC) with a sinusoidal charging-discharging lithium-ion battery for electric vehicles in single-phase three-wire distribution feeders. The dc-capacitor current of the three-leg pulse-width modulated (PWM) rectifier, which is included in the SC, is detected, and then added to the reference value...
Recent years, multilevel inverters have become more attractive for researchers due to low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a three-phase cascaded H-bridge quasi-switched-boost inverter (CHB-qSBI). The advantages of the proposed inverter are as follows: buck-boost voltage with single stage power conversion, reduced...
This paper describes a new modulation concept for the uni- and bidirectional SWISS rectifier, which mitigates ac input current distortions at the mains voltage sector boundaries. An analytical model is derived and compared to simulations, which allows an estimation of the distortion's magnitude from design parameters, showing that these distortions increase the input current total harmonic distortion...
This paper proposes the control strategy of a multi-input boost converter for renewable energy system applications. The desired high output voltage with a constant level can be achieved using the multi-input boost converter. The low multi-input voltage sources are generated from renewable energy sources such as PV modules and wind turbines. The control of the multi-input boost converter is based on...
Modulation techniques for the modular multilevel converter consider that the total number of sub-modules in the phase-leg is, either instantaneously or on average, equal to N balancing the capacitor voltages to a constant reference. This paper proposes an offset PWM technique that utilises the total number of the SMs in the arms of the MMC, particularly under low modulation indices. The result is...
A modified hybrid multilevel converter which is a combination of T-type converter and H-bridge is present in this paper. Beside increase output levels, another merit of this topology is larger output range compared with traditional two-level converter. Depending on the value of H-bridge floating capacitor voltage, the converter can produce 5-level, 7-level, or 9-level output voltage. The H-bridge...
This paper presents a new type of cascaded PWM ac-ac converter with phase-shift PWM control. It can reach high output voltage by cascading single-phase units of low voltage rating devices. The proposed converter does not sense current/voltage polarity, and does not require current/voltage sensors and lossy snubbers for commutation, thereby the control complexity can be decreased. It has no shoot-through...
Three phase converters are favorable for high power grid connected systems. In photovoltaic (PV) application, it is possible to remove the transformer from the PV system in order to reduce size, losses, and cost; and improve the efficiency. In other hand, presence of the parasitic capacitor between the panel's metal frame and cells causes the leakage current issue. The leakage current increases current...
Single-stage DC-AC power converters are gaining higher popularity due to their merits compared to the conventional two-stage DC-AC conversion systems. One of these converters is the buck-boost voltage source inverter. This converter has some merits over the other single stage DC-AC power converters in terms of passive component-count, overall gain ratio, and voltage stresses. This paper studies the...
Four-level hybrid-clamped (4L-HC) inverter is a newly proposed topology which is suitable for high-performance medium-voltage drives. This paper proposes a multi-objective optimization strategy for this 4L-HC inverter. The central DC-link capacitor and flying capacitor voltages are regulated by a modified phase-shifted PWM. The upper and lower capacitor voltages are balanced by zero-sequence voltage...
This paper focuses on the determination of suitable carrier based pulse width modulation (PWM) switching and control methods for grid connected modular multilevel converters (MMCs). Characterization of various level-shifted and phase-shifted carrier based PWM methods are provided in terms of output voltage waveforms both for N+1 and 2N+1 level output phase voltages. Carrier based PWM method based...
In this paper, a reversible multilevel nine-leg converter for three-phase applications is investigated. This topology can be applied in line voltage regulator, power factor correction (PFC) and uninterrupted power supplies (UPS). It is composed of three single-phase three-leg converters with a leg shared by both load and grid sides. Suitable modelling, a pulse-width modulation (PWM) strategy based...
Compared with the conventional buck-boost three-level inverters, the Z-source neutral-point-clamped (NPC) inverters have more simple structure with improved output waveform quality. But the neutral-point potential unbalance problem is still a drawback for their applications. Based on the research of SPWM modulation method and the analysis of the effect of the shoot-through states on the neutral-point...
This paper deals with compensation performance of an active load balancer (ALB) with the constant DC capacitor voltage control based strategy under multiple feeders. Instantaneous power flow into the ALB show that the balanced source currents with a unity power factor are obtained on the feeder that is connected to the ALB. Thus the ALB is not over loaded although the constant DC capacitor voltage...
This paper presents modified topologies for the Z-source inverter. The main objective of the modifications are to get higher boost factor, less voltage stress across the switches as well as reduction of the number of passive components. Two types of inverter topologies are presented in this paper. They are ripple-input current proposed inverter (r-proposed inverter) and continuous-input current proposed...
A simple flying-capacitor voltage balancing method for nested neutral point clamped (NNPC) inverter is proposed in this paper. The NNPC inverter is a newly developed four-level voltage source inverter (VSI) with new topology. There are two flying-capacitors in series in each leg in the NNPC inverter. The voltage across each capacitor should be controlled to balance at one-third of DC bus voltage to...
In this paper a new five-level hybrid-clamped converter with reduced number of clamping devices is introduced. Only two active switches and two flying capacitors are used for clamping per phase. The operating method is introduced and phase-shifted pulse width modulation (PS-PWM) is used to control this converter. A detailed analysis of the average currents through the flying capacitors and neutral...
Bulky capacitors are often needed in DC systems to smooth voltage ripples, which reduces the power density and system reliability considerably. In this paper, a Ripple Eliminator (RE) that is a bidirectional buck-boost converter terminated with an auxiliary capacitor is proposed to reduce voltage ripples after connecting it to the DC bus. A controller is proposed to transfer the voltage ripples on...
The paper presents an analysis of a novel 13-level inverter, which consists of three cascaded H-bridges per phase. Each H-bridge produces 5-level voltages. The proposed topology has only two bi-directional and four standard IGBT switches in each 5-level H-bridge. The significant advantages of the proposed inverter are simpler control and lower number of switches than in the standard neutral point...
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