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Multilevel dc-dc converters making use of high-frequency transformers are suitable for integration in solid-state solutions for applications in electric power distribution systems. This paper presents a simplified switching scheme for three-level full-bridge dc-dc converters that enables zero-voltage and zero-current switching of all the main power devices. It describes the main operational modes and design equations of the converter as well as provides simulation and experimental results to demonstrate the feasibility of the proposed ideas. Index Terms--Distributed energy resources, multilevel converters, soft-switching converters, three-level (3L) full bridge (FB), zero-voltage zero-current switching (ZVZCS).

Distributed energy resources (DERs) are becoming integral components of electric power distribution systems. In most cases, an isolated dc-dc converter forms part of the interface required to connect the DER output to the distribution system. Operation of the converter at high switching frequencies results in size reduction of passive components at the expense of increased switching losses. However, silicon carbide (SiC) power devices have the potential of operating at high switching frequencies without significant loss penalty because of their fast switching times and ability to work at high temperatures when compared to similar Si devices. SiC diodes have already displayed the ability to offer more ideal diode behavior than Si diodes. Engineering samples of SiC MOSFETs are depicting lower switching losses and conduction losses over Si MOSFETs. This display is making SiC devices attractive for dc-dc converters used to connect DERs to the distribution system. This paper particularly deals with the design of a 300-W 100-kHz dc-dc full-bridge converter using zero-voltage zero-current switching for comparison of SiC MOSFETs and diodes against Si MOSFETs and diodes. Index Terms--DC-DC converters, distributed energy resources (DERs), full bridge, silicon carbide (SIC) MOSFET, zero-current zero-voltage switching.

This paper proposes a novel method to generate a sinusoidal waveform synchronized with any measurable periodic signal whose frequency is within a given neighborhood. The synthesized sinusoidal signal could be used as a reference current for certain applications of parallel active power filters or any other where such synchronization would be necessary (e.g., ac/dc converters for renewable energy resources, power factor correctors, power supplies, UPS, etc.) The method is based on the behavior of a dynamical system and avoids employing the usual combination of phase-locked loop (PLL) and lookup table found in most parallel active filters synthesizing a sinusoidal source current (a table also means using significant storage memory). The novel method produces two high-quality sinusoidal waveforms that are in quadrature and is applicable to those parallel active filters whose control methodology is in the [alpha][beta] reference frame, or alternatively, it produces three sinusoidal waveforms shifted 120 degrees for designs that work in the abc frame. Here, a (2n + 1)th order implementation is described, including a proof of convergence. For its most simple implementation (n = 1), simulated and experimental results are included.

This paper evaluates the capability of SiC power semiconductor devices, in particular JFET and Schottky barrier diodes (SBD) for application in high-temperature power electronics. SiC JFETs and SBDs were packaged in high temperature packages to measure the dc characteristics of these SiC devices at ambient temperatures ranging from 25 [degrees]C (room temperature) up to 450 [degrees]C. The results show that both devices can operate at 450 [degrees]C, which is impossible for conventional Si devices, at the expense of significant derating. The current capability of the SiC SBD does not change with temperature, but as expected the JFET current decreases with rising temperatures. A 100V, 25W dc-dc converter is used as an example of a high-temperature power-electronics circuit because of circuit simplicity. The converter is designed and built in accordance with the static characteristics of the SiC devices measured under extremely high ambient temperatures, and then tested up to an ambient temperature of 400 [degrees]C. The conduction loss of the SiC JFET increases slightly with increasing temperatures, as predicted from its dc characteristics, but its switching characteristics hardly change. Thus, SiC devices are well suited for operation in harsh temperature environments like aerospace and automotive applications. Index Terms--dc-dc converter circuit, device characterization, high temperature operation, packaging, silicon carbide (SIC) device.

This paper presents a theoretical analysis for canceling common-mode (CM) voltages for induction motor (IM) drives using a CM transformer with active circuitry. The design methodology and the practical implementation are presented for motor drives rated 460 V or higher. To verify the design approach, an implementation example and experimental results for a 460-V motor drive system are presented. Index Terms--Active circuits, electromagnetic interference (EMI), induction motor (IM) drives, leakage currents.

The use of environmentally clean photovoltaic (PV) dispersed generation will become more widespread in the future due to anticipated cost reductions in PV technology. This paper summarizes the results of a power quality (PQ) study performed on a PV generator in order to estimate the effects that inverter-interfaced PV dispersed generation might have upon the quality of electric power. Different interpretations of the harmonic distortion limits set in the IEEE 519-1992 standard are performed together with a comparison with the BC Hydro's harmonic current limits. This paper also includes a statistical analysis of all measurements recorded with the help of two PQ monitors, an evaluation of the results from a connection/disconnection test, and harmonic simulation results. Index Terms--Dispersed generation, harmonic distortion, IEEE standards, IEEE 519-1992, power quality, photovoltaic power generation.