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Minimization of the dc capacitor is an essential step towards developing and manufacturing compact low-cost hybrid electric vehicle (HEV) converter/inverter systems for high temperature operation, long life and high reliability. Previously, most papers have been focused on the AC-DC-AC pulse-width modulation (PWM) converters with relatively complicated close-loop control methods, while few papers...
This paper presents a configuration for single-phase to three-phase power conversion. The proposed topology combines the principle of series active power filter and the concept of Z-source inverter, which guarantees the high voltage requirement of the three-phase load. A comparison with the direct solution shows that with the proposed topology it is possible to reduce the voltage ratings of the power...
Multi-level inverter technology has emerged recently as a very important alternative in the area of medium-voltage high-power energy control. Due to higher number of dc voltage sources, lower EMI, requirement of semiconductor power devices with less blocking voltage, lower % THD in output voltage and less stress on insulation, they are widely used. However, it has some disadvantages as complicated...
Modular multilevel converter (MMC) is a highly attractive topology for medium and high voltage power conversions without transformers. The main problem is the voltage balancing on floating capacitors. This paper presents a solution using phase-disposition carrier PWM method to solve the voltage balancing of a novel MMC, which is derived from the generalized multilevel inverter topology and introduced...
This paper compares and analyzes two control methods (pulse width and phase shift modulation) for a new type of step-up DC/DC converters with galvanic isolation - the quasi-Z-source inverter (qZSI) based DC/DC converter. The proposed converter is suitable for applications, where the wide range of voltage gain is demanded, e.g. with renewable energy sources (fuel cells, photovoltaic cells), in telecom,...
This paper analyses the influence of the modulation technique on the size of the grid EMI filter inductor in a full bridge converter for photovoltaic systems. Additionally, the use of an alternative modulation technique is proposed which exhibits the best compromise concerning efficiency, current quality and EMI filter size.
When feeding an induction motor by a PWM-inverter through long cables, reflections occur and overvoltages may arise. Using a terminator in parallel with the motor, the overvoltages are reduced. An analytical calculation of the motor voltage is obtained using transmission line theory. Simulations and measurements allow to verify the results.
Multilevel converters topologies present important benefits when they are used on medium and high power applications. However, it is necessary to design new alternating methods to control easily the internal dynamics of the converter. This paper presents a new voltage balancing strategy for a flying capacitor multilevel converter in conjunction with a space vector modulation technique. The advantages...
A novel converter using three switching devices, which has a DC input and two single-phase AC outputs, is proposed. A PWM control scheme for the proposed converter is also described in this paper. Moreover, simulation verification of the proposed converter is conducted. As a result, it is shown that the proposed converter can convert electric power bidirectionally among a DC terminal and two AC terminals...
In general, chopper circuits are necessary for the inverter system whose input voltage fluctuates such as solar power energy, wind power energy, capacitor energy and so on. Therefore, the inverter system becomes larger, the energy losses of power converter increase, and control circuit is complicated. In this paper, to overcome these problems, a control scheme of PWM inverter to get the constant R...
A novel hybrid cascade H-bridge converter is presented in which cascaded H-bridge cells and one three-phase two-level converter with a flying capacitor are connected together. The output voltage will be increased while the number of isolated DC bus can be reduced. PWM control method and flying capacitor voltage balancing algorithm are analyzed. Simulation results verified the proposed performance.
A general problem in the double PWM converter is the voltage unbalance of the dc-link capacitors. This unbalance distorts the waveforms of the output voltage and current. Furthermore, it will lead to instability of the inverter system. Based on the analysis for the unbalance problem, a novel feedback control strategy of DC capacitor voltage deviation is proposed in this paper. The method does not...
This paper presents an analysis and the design of an off grid PV system for providing electricity for remote area. The system composed of dc-dc multilevel boost converter (MLBC) which is used for extracting maximum power from the cell. It has been chosen to generate three dc voltages at its output terminal. In addition to, a multilevel dc link inverter suitable for the generated dc bus voltages. The...
An accurate theory of calculating the DC link capacitor voltage ripple and current ripple for SPWM inverters and PWM rectifiers, which are most commonly used in series hybrid electric bus (SHEB) converter/inverter systems at low speed, is presented in the paper. Most of all, the results are analyzed and summarized into graphs, which helps to find the right capacitance value for a given voltage ripple...
Analysis and minimization of input current and voltage ripples of five-phase PWM inverters are presented in this paper. The analytical expressions for the RMS value of input current and voltage ripples as a function of the PWM reference signal are derived. Different to three-phase PWM inverters, it is shown that pure sinusoidal is the optimum reference signal that produces minimum input voltage ripple...
In this paper, the novel circuit topology of half-bridge soft switching PWM DC-DC power converter with a high frequency planar transformer link was presented. The operating principle and switching pattern of the half-bridge soft switching PWM DC-DC power converter described for 40 kHz, 36 V and 400 A output were illustrated and discussed for low voltage and large current output applications such as...
Renewable energy has been a great concern to obtain ecological society that can continuously grow. As an attractive solution, the fuel cell cogeneration system has been attracted and some first products have been developed in Japan and in some other centuries/areas. A product in Japan, which is the first developed system and few hundreds of the sets are under operation in Japanese homes, has been...
This paper mentions the static characteristics of pulse-link DC-AC converter for fuel cells, and considers the input current-ripple reduction method. Fuel cells have weakness about current-ripple because the chemical reaction time is much slower than commercial frequency. Therefore, the input current-ripple reduction is essential factor in the DC-AC converter for fuel cells applications. Input current-ripple...
Reliability and fault tolerant operation are key aspects in high power drives, specially when these drives are used to operate critical loads, as downhill conveyors. This paper presents a solution for the operation under internal fault of high power regenerative cascade multicell converter, which allows to operate temporally in normal conditions or to turn off the equipment in a controlled way. Previous...
An analysis of the efficiency of AC/DC/AC diode-clamped multilevel converters is presented, where commanded and suitable variations of the DC-link voltages are proposed in order to decrease the energy losses. The study is carried out also aiming at the correct DC-link capacitor voltage balance, obtained with additional chopper stages together with a new PWM technique, considering both inverter and...
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