Peter M. Barbosa

Technology trends toward a system-in-a-module in power electronics

Currently, assemblies of power semiconductor switches and their associated drive circuitry are available in modules. From a few 100 watts downward, one finds silicon monolithic technology as the integration vehicle, while upward into the multi-kilowatt range, mixed mode module construction is used. This incorporates monolithic, hybrid, surface mount and wirebond technology. However, a close examination of the applications in motor drives and power supplies indicates that there has been no dramatic volume reduction of the subsystem. The power semiconductor modules have shrunk the power switching part of the converter, but the bulk of the subsystem volume still comprises the associated control, sensing, electromagnetic power passives and interconnect structures. The paper addresses the improvement of power processing technology through advanced integration of power electronics. The goal of a subsystem in a module necessitates this advanced integration. The central philosophy of this technology development research is to advance the state of the art by providing the concept of integrated power electronics modules (IPEMs). The technology underpinning such an IPEM approach is discussed. The fundamental functions in electronic power processing, the materials, processes and integration approaches and future concepts are explained.

A zero voltage switching three-level DC/DC converter

A novel zero voltage switching (ZVS) three-level (TL) DC/DC power converter is presented in this paper. The converter uses a flying capacitor in the primary side to allow operation with phase-shift control and in this way achieves ZVS for all the switches. The principle of operation of the converter is analyzed and verified on a 6 kW, 100 kHz experimental prototype. Additionally, this paper presents improvement of the proposed converter by using different ZVS techniques.

A zero voltage and zero current switching three level DC/DC converter

This paper presents a novel zero voltage and zero current switching (ZVZCS) three-Level (TL) DC/DC power converter. This converter overcomes the drawbacks presented by the conventional zero voltage switching (ZVS) three-level converter, such as high circulating energy, severe parasitic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an auxiliary circuit to reset the primary current during the freewheeling stage to achieve ZCS for the inner switches. The principle of operation and the DC characteristics of the new converter are analyzed and verified on a 6kW, 100 kHz experimental prototype.

A primary-side-assisted zero-voltage and zero-current switching three-level DC-DC converter with phase-shift control

A new primary-side-assisted zero-voltage and zero-current switching (ZVZCS) three-level DC-DC converter with phase-shift control is proposed. Three-level converters show promise for use in high-voltage applications, and ZVZCS is a very effective means for reducing switching losses. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to achieve ZCS for the inner leg. It has a simple and robust structure, and offers soft-switching capability even in short-circuited conditions. The proposed converter was verified by experiments using a 6 kW prototype designed for communication applications and operating at 100 kHz.

Comparison study of fixed-frequency control strategies for ZVS DC/DC series resonant converters

Nowadays, resonant power converters are not commonly used, mainly due to their comparatively high conduction losses and component stresses. However, they are useful for some specific applications requiring low noise, high power density or high-frequency operation. In these applications, MOSFETs are the usual devices for which ZVS operation is recommended. This normally requires a switching frequency above the resonant frequency, so higher conduction and turn-off losses may be expected. In this paper, three different fixed-frequency control strategies for the ZVS full-bridge series resonant converter are analyzed and compared, in order to determine which one achieves the least conduction and turn-off losses, without losing ZVS and considering input-voltage and load variations.

An integrated approach to power electronics systems

Power electronics systems are typically designed and manufactured using nonstandard parts, which results in labor-intensive manufacturing processes and increased cost. As a possible way to overcome these problems, this paper provides an overview of an integrated approach to design and realize power electronics systems, aiming at improved performance, reliability, manufacturability and cost effectiveness. A brief discussion is presented on the technology barriers that limit the rapid growth of power electronics, such as passive components and packaging techniques. It is also discussed the technology advancements needed to improve the characteristics of power electronics systems, such as increased levels of integration, standardization of parts and improved packaging techniques for enhanced thermal management and electrical performance. The technologies being developed for the realization of integrated systems include planar metalization to allow three-dimensional structural integration of power devices and control functions, integration of power passives, and integration of electrical/thermal design tools.

Design aspects of paralleled three-phase DCM boost rectifiers

The interleaved operation of paralleled boost rectifiers reduces the amplitude of the input current ripple and increases its effective frequency. As a consequence, the size and volume of the input EMI filter can be reduced. This work provides a detailed analysis of the fundamental component of the input current ripple of the interleaved system along with curves that facilitate the input EMI filter design. It also presents an equivalent circuit model that is valid at low frequency and can be used to design the voltage loop control. The experimental results are provided for a prototype rated at 220 V input phase voltage, 8 kW, 40 kHz, and 800 V output voltage. The harmonic distortion of the paralleled system complies with IEC 61000-3-2 Class A standard.

Integration of electromagnetic passive components in DPS front-end DC/DC converter - a comparative study of different integration steps

In most of the power electronics converters, the overall footprint and profile of the whole system are in large part determined by the footprint and profile of the passive components and the interconnections between them. Integrated magnetics, planar magnetics and passive integration techniques have been topics of research for the past few years to reduce the parts count, footprint and profile of the passive components, hence increasing the power density of the whole converter. This becomes especially prominent in the distributed power system (DPS) front-end converters, as the trend is moving from 2U (1U=1.75 inches) standard toward 1U standard. This paper presents a comparative study of the integration steps of passive components of an asymmetrical half bridge circuit (AHBC) for DPS front-end DC/DC converter application. Four AHBC converters using discrete passive components, nonplanar integrated magnetic components, planar integrated magnetic components and passive integrated power electronic module (IPEM), respectively, are constructed and tested. Comparisons are made from the viewpoints of volume, profile, efficiency, EMI and thermal performances of the four converters. The experimental result shows that the passive IPEM, which integrates all the passive components, has much higher power density, lowest profile, lower temperature rise and similar efficiency.

Analysis and evaluation of the two-switch three-level boost rectifier

This paper presents the analysis and evaluation of a two-switch boost rectifier operated in the discontinuous conduction mode (DCM). The three-level structure of the topology discussed in the paper allows the use of devices with reduced voltage ratings, such as 600 V MOSFETs. The analysis shows that the harmonic distortion created by the two-switch topology is lower than that of the single-switch three-phase DCM boost rectifier. The interleaving technique is used to reduce the size of the input filter by providing input current ripple cancellation. This paper also compares the two-switch three-level topology against its benchmark, which consists of three single-phase front-end modules implemented with single-phase continuous conduction mode (CCM) boost rectifiers in the power factor correction (PFC) stage. The discussion is supported by simulation and experimental results.

A three-level isolated power factor correction circuit with zero voltage switching

This paper presents a new three-level converter for three-phase power factor correction and output voltage regulation in a single stage of power conversion. The AC side of the proposed converter operates in DCM to obtain power factor correction. On the other hand, the DC side of the converter may operate either in CCM or DCM. The interest in operating the DC side in DCM is to limit the maximum intermediate bus voltage to realistic values. The paper presents the PWM and the phase-shift control versions of the proposed converter. All the power switches operate under a zero-voltage turn-on condition. The harmonic distortion generated by the proposed converter is lower than the distortion produced by the conventional three-phase single-switch DCM boost rectifier. Theoretical analysis, design guidelines, and experimental results are provided for a prototype rated at 3 kW and operated at 100 kHz.