Search

In this paper, three different inverters: conventional pulsewidth modulation (PWM) inverter, dc-dc boosted PWM inverter, and Z-source inverter were investigated and compared for fuel cell vehicle application. Total switching device power, passive components requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, the constant power speed ratio, and the efficiencies of the different inverters for fuel cell vehicle powered by the same fuel cell were conducted. The comparisons show that the Z-source inverter is very promising in applications when the boost ratio is low (1-2). Index Terms--DC-DC power conversion, fuel cells, inverter.

This paper proposes a Z-source inverter system for a split-phase grid-connected photovoltaic system. The operation principle, control method, and characteristics of the system are presented. A comparison between the new and traditional system configurations is performed. Simulation and experimental results are also shown to verify the proposed circuit and analysis. Index Terms--Photovoltaic (PV), power conditioning, MPPT, Z-source inverter.

This paper presents a novel control method to lower the harmonic components of the conventional voltage balancing control for the multilevel converters. The harmonic components in the voltage balancing control theory are analyzed in detail. A revised control method based on the line-line voltage redundancy of the three-phase inverter is proposed to lower the harmonic components of both the converter and inverter side. The proposed method can significantly reduce the harmonic components while keeping the switching frequency nearly the same. Simulation and experimental results are provided to show the validity of the theory. Index Terms--Multilevel converter, total harmonic distortion (THD), voltage balancing control.

This paper presents a low-cost approach to power factor correction (PFC) of single-phase diode rectifiers using a series active filter. Comparing with the traditional PFC, the proposed PFC has lower requirements of power device ratings, which leads to lower cost, higher efficiency, and lower electromagnetic interference. It also can eliminate the bulky inductor needed in the traditional PFC. The topology, operation principle, and application issues of the proposed PFC are analyzed in this paper. The control strategy is discussed in detail and simulation results are provided. A 1-kW prototype is built up and the experimental results are presented to verify the analysis. Index Terms--Adjustable-speed drive, heating, ventilating, and air conditioning (HVAC), power factor correction (PFC), series active filter.

The high installation cost is the major obstacle of the commercialization of the solid oxide fuel cell for distributed power generation. This paper presents a new low cost 10-kW converter system to overcome this obstacle. The proposed system consists of an isolated dc-dc converter to boost the fuel cell voltage to 400 V dc and a pulse-width modulated inverter with filter to convert the dc voltage to two split-phase 120-V ac. The dc-dc converter uses phase shifting to control power flow through a transformer with a metal oxide semiconductor field effect transistor full bridge on the low voltage side and a voltage doubler on the high voltage side. One IPM is used to realize the voltage doubler and the dc-ac inverter. Compared to the existing fuel cell converter systems, the proposed circuit has low cost, less component count, smaller size, and reduced dc-dc converter peak current. Simulation and experimental results are demonstrated. Index Terms--DC-DC converter, IPM, solid oxide fuel cell (SOFC), two split-phase, voltage douler.

Power flow control is important in power systems and recently becomes more urgent because of the deregulation and 2003 blackout. This paper presents a novel configuration of unified power flow controller. The proposed configuration has several unique features and advantages over the conventional configuration. As a result, cascade multilevel inverter can be used in the new configuration to lower the cost, volume, and increase the reliability of the system. Analysis and simulation results will be presented. Index Terms--Cascade multilevel inverter, unified power flow controller (UPFC).

A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one dc voltage source. This new inverter can operate as a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-frequency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation results demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering). Index Terms--Cascaded inverter, multilevel inverter, three-level inverter.

This paper presents a regenerative passive snubber circuit for pulse-width modulation (PWM) inverters to achieve soft-switching purposes without significant cost and reliability penalties. This passive soft-switching snubber (PSSS) employs a diode/capacitor snubber circuit for each switching device in an inverter to provide low dv/dt and low switching losses to the device. The PSSS further uses a transformer-based energy regenerative circuit to recover the energy captured in the snubber capacitors. All components in the PSSS circuit are passive, thus leading to reliable and low-cost advantages over those soft-switching schemes relying on additional active switches. The snubber has been incorporated into a 150 kVA PWM inverter. Simulation and experimental results are given to demonstrate the validity and features of the snubber circuit. Index Terms--EMI, PSSS, PWM, soft switching inverters.

This paper presents a new zero-voltage-switching (ZVS) bidirectional dc-dc converter. Compared to the traditional full and half bridge bidirectional dc-dc converters for the similar applications, the new topology has the advantages of simple circuit topology with no total device rating (TDR) penalty, soft-switching implementation without additional devices, high efficiency and simple control. These advantages make the new converter promising for medium and high power applications especially for auxiliary power supply in fuel cell vehicles and power generation where the high power density, low cost, lightweight and high reliability power converters are required. The operating principle, theoretical analysis, and design guidelines are provided in this paper. The simulation and the experimental verifications are also presented. Index Terms--Auxiliary power supply, dc-dc converter, fuel cell vehicle, power generation, TDR, ZVS.

High gain bidirectional dc–dc converter with high efficiency and high power density is a much desired circuit in any converter/inverter system. It is well known that switched capacitor circuits that are variants of the Dickson converter are suitable candidates for such a system. Modular design, absence of external magnetic components, and high efficiency are some of the features that make them suitable candidates. But, the inability to provide fractional and variable voltage gains at high efficiency during normal operation severely limits their application. It also leads to higher voltage stress in the overall system. The aim of this paper is twofold. First, a generalized modular switched capacitor converter, the “(n/m)X converter,” which is a variant of the original Dickson converter is introduced. Using this generalized configuration, the converter can be designed for a required fractional gain. Next, two different methods to enable dynamic variation in gain with high efficiency using the (n/m)X converter are proposed. Detailed analysis, design steps, equivalent circuits, and experimental results for a 1 kW prototype of a variable (4/0.5)X boost converter validate the proposed theory. A peak measured efficiency of over 95% is achieved for the prototype. The design framework and analysis in this paper can be extended to a generic (n/m)X converter. [ABSTRACT FROM AUTHOR]

In this paper, three different inverters: conventional pulsewidth modulation (PWM) inverter, dc-dc boosted PWM inverter, and Z-source inverter were investigated and compared for fuel cell vehicle application. Total switching device power, passive components requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, the constant power speed ratio, and the efficiencies of the different inverters for fuel cell vehicle powered by the same fuel cell were conducted. The comparisons show that the Z-source inverter is very promising in applications when the boost ratio is low (1–2). [ABSTRACT FROM AUTHOR]

This paper proposes a Z-source inverter system for a split-phase grid-connected photovoitaic system. The operation principle, control method, and characteristics of the system are presented. A comparison between the new and traditional system configurations is performed. Simulation and experimental results are also shown to verify the proposed circuit and analysis. [ABSTRACT FROM AUTHOR]

This paper presents a novel control method to lower the harmonic components of the conventional voltage balancing control for the multilevel converters. The harmonic components in the voltage balancing control theory are analyzed in detail. A revised control method based on the line-line voltage redundancy of the three-phase inverter is proposed to lower the harmonic components of both the converter and inverter side. The proposed method can significantly reduce the harmonic components while keeping the switching frequency nearly the same. Simulation and experimental results are provided to show the validity of the theory. [ABSTRACT FROM AUTHOR]

The high installation cost is the major obstacle of the commercialization of the solid oxide fuel cell for distributed power generation. This paper presents a new low cost 10-kW converter system to overcome this obstacle. The proposed system consists of an isolated dc-dc converter to boost the fuel cell voltage to 400 V dc and a pulse-width modulated inverter with filter to convert the dc voltage to two split-phase 120-V ac. The dc-dc converter uses phase shifting to control power flow through a transformer with a metal oxide semiconductor field effect transistor full bridge on the low voltage side and a voltage doubler on the high voltage side. One IPM is used to realize the voltage doubler and the dc-ac inverter. Compared to the existing fuel cell converter systems, the proposed circuit has low cost, less component count, smaller size, and reduced dc-dc converter peak current. Simulation and experimental results are demonstrated. [ABSTRACT FROM AUTHOR]

This article focuses on distributed power generation. The worldwide electric utility generation is estimated at over 3,000,000 installed megawatts (MW) and is growing by more than 80,000 MW per year. In the U.S. and many other parts of the world, retail competition is increasing and the power generation segment has been or is being deregulated and opened up to competition. Building new central generating plants is or will be a riskier proposition than it was for regulated utilities of the past. This new deregulated world has caused and will continue to cause the utility and new generating companies to seek opportunities for constructing smaller generating plants, closer to the customer, which reduce the risk and increase predictability of utilization.