In the first part of this paper, three-phase power factor correction (PFC) rectifier topologies with sinusoidal input currents and controlled output voltage are derived from known single-phase PFC rectifier systems and/or passive three-phase diode rectifiers. The systems are classified into hybrid and fully active pulsewidth modulation boost-type or buck-type rectifiers, and their functionality and basic control concepts are briefly described. This facilitates the understanding of the operating principle of three-phase PFC rectifiers starting from single-phase systems, and organizes and completes the knowledge base with a new hybrid three-phase buck-type PFC rectifier topology denominated as Swiss Rectifier. Finally, core topics of future research on three-phase PFC rectifier systems are discussed, such as the analysis of novel hybrid buck-type PFC rectifier topologies, the direct input current control of buck-type systems, and the multi-objective optimization of PFC rectifier systems. The second part of this paper is dedicated to a comparative evaluation of four rectifier systems offering a high potential for industrial applications based on simple and demonstrative performance metrics concerning the semiconductor stresses, the loading and volume of the main passive components, the differential mode and common mode electromagnetic interference noise level, and ultimately the achievable converter efficiency and power density. The results are substantiated with selected examples of hardware prototypes that are optimized for efficiency and/or power density.

The Essence of Three-Phase PFC Rectifier Systems—Part II

In this paper, three-phase PFC rectifier topologies with sinusoidal input currents and controlled output voltage are derived from known single-phase PFC rectifier systems and/or passive three-phase diode rectifiers. The systems are classified into hybrid and fully active PWM boost-type or buck-type rectifiers, and their functionality and basic control concepts are briefly described. This facilitates the understanding of the operating principle of three-phase PFC rectifiers starting from single-phase systems, and organizes and completes the knowledge base with a new hybrid three-phase buck-type PFC rectifier topology denominated as Swiss Rectifier. In addition, analytical formulas for calculating the current stresses on the power semiconductors of selected topologies are provided, and rectifier systems offering a high potential for industrial applications are comparatively evaluated concerning the semiconductor stresses, the loading and volume of the main passive components, and the DM and CM EMI noise level. Finally, core topics of future research on three-phase PFC rectifier systems are discussed, such as the analysis of novel hybrid bucktype PFC rectifier topologies, the direct input current control of bucktype systems, the multi-objective optimization of PFC rectifier systems concerning efficiency and power density, and the investigation of the system performance sensitivity to semiconductor and passive components technology.

The essence of three-phase PFC rectifier systems

An open-winding power conversion system with two conventional six-switch voltage-source converters (VSC) affords operation with a lower volt-ampere (VA) rating of each device for a given power rating, as well as a degree of fault tolerance. The disadvantages of such a configuration include a higher total device VA rating and increased conduction loss as compared to a single Y/Δ-connected VSC. In certain ac-dc applications, such as telecommunications, wind, and aerospace generator drives, it is desired to have regulated input currents and output voltage, but regenerative operation is either not required or prohibited. For such applications, an alternative open-winding power converter is proposed in this paper where half-controlled converter (HCC) is employed at each end of an open-winding structure. The resultant total switch count and total VA rating are reduced by half, compared to using full bridges. Besides, the basic advantages of an open-winding configuration, use of HCCs also guarantees immunity to dc-bus shootthrough and simplifies the gate drive circuit. The total VA rating of the proposed topology is found to be 42% less than a six-switch VSC. The operating principle, control method, and analysis with simulation and experimental results of the proposed topology in both a grid-tied rectifier application and a PM generator application are illustrated in this paper.

Open-Winding Power Conversion Systems Fed by Half-Controlled Converters

This paper presents the analysis and operation of a three-phase pulsewidth modulation rectifier system formed by the star-connection of three single-phase boost rectifier modules (Y-rectifier) without a mains neutral point connection. The current forming operation of the Y-rectifier is analyzed and it is shown that the phase current has the same high quality and low ripple as the Vienna rectifier. The isolated star point of Y-rectifier results in a mutual coupling of the individual phase module outputs and has to be considered for control of the module dc link voltages. An analytical expression for the coupling coefficients of the Y-rectifier phase modules is derived. Based on this expression, a control concept with reduced calculation effort is designed and it provides symmetric loading of the phase modules and solves the balancing problem of the dc link voltages. The analysis also provides insight that enables the derivation of a control concept for two phase operation, such as in the case of a mains phase failure. The theoretical and simulated results are proved by experimental analysis on a fully digitally controlled, 5.4-kW prototype.

Analysis and Control of a Three-Phase, Unity Power Factor $Y$ -Rectifier

Transfer efficiency of a wireless power transfer (WPT) system is tightly related to the load, which varies greatly in a wide range during the charging process. Generally speaking, dual-sided control strategies are commonly applied to overcome the load variation and improve system efficiency. However, the system may suffer from hard switching, high control complexity, and auxiliary dc/dc converters. In this article, a dual-sided control strategy based on mode switching is proposed to approach an optimal load impedance, zero-voltage switching of all mosfet s in WPT system, and a required output. In this control strategy, the output voltage of the inverter is adjusted in a wide range by switching the operation mode of the inverter to approach the optimal load impedance. The output current/voltage is regulated by the active rectifier control. Besides, a novel phase-locked method is proposed for the semi-bridgeless active rectifier control, which is simpler compared with the traditional phase-locked method. Finally, a 500-W prototype is built to verify the theoretical analysis, and the peak system efficiency of 93.9% is gained with k = 0.23.

A Dual-Sided Control Strategy Based on Mode Switching for Efficiency Optimization in Wireless Power Transfer System

The basic principle of operation of a three-phase PWM rectifier system formed by star-connection of three single-phase three-level PWM rectifier modules (three-level y-rectifier) is discussed based on space vector calculus. The mains current ripple resulting for synchronized operation of the phase modules is calculated and comparatively evaluated against a direct three-phase PWM (Vienna) rectifier realization. The current stresses on the power semiconductors and on the passive power components are calculated analytically in order to provide a basis for the system dimensioning. A novel concept for controlling the y-rectifier is proposed which guarantees a symmetric loading of the phase modules and allows to continue the system operation also in case of heavily unbalanced mains voltage and/or for a failure of a mains phase. Finally, the advantages and drawbacks of the y-rectifier concept are summarized and topics of further research are identified.

Analysis and comparative evaluation of a three-phase three-level unity power factor y-rectifier

In this paper, the voltage and current stress of a delta-connection of three single-phase boost-type unity power factor rectifier modules (Δ-Rectifier) is analyzed in order to perform a design comparable to a direct three-phase three-level six-switch unity power factor (conventional) rectifier system. The conduction losses of the power semiconductors are calculated using analytical approximations of the average and RMS values of the component currents, the switching losses are taken from previous experimental investigations. Based on this data an overview of the estimated power losses is given for the Δ-rectifier as well as for the conventional rectifier for 10 kW output power, 800 VDC output and 320 V/400 V/480 V/530 V (RMS, line-to-line) mains voltage. These investigations finally lead to efficiency and component count figures. Furthermore, special attention is paid to the control of the whole three-phase system, including the DC/DC converter output stages of the line-to-line modules of the Δ-rectifier. Finally, topics of the continuation of the research are identified as, e.g., the realization of a prototype in order to verify the theoretical results experimentally also for unbalanced mains voltage conditions and with nonideal components such as nonlinear input inductors employing iron powder cores and the analysis of a Δ-rectifier being formed by single-stage SEPIC-type line-to-line modules.

Evaluation of a delta-connection of three single-phase unity power factor rectifier modules (/spl Delta/-rectifier) in comparison to a direct three-phase rectifier realization

In this paper the voltage and current stress of a delta-connection of three single-phase boost-type unity power factor rectifier modules (Δ-Rectifier) is analyzed in order to perform a design comparable to a direct three-phase three-level six-switch unity power factor (conventional) rectifier system. The conduction losses of the power semiconductors are calculated using analytical approximations of the average and rms values of the component currents, the switching losses are taken from previous experimental investigations. Based on this data an overview of the estimated power losses is given for the A-Rectifier as well as for the conventional rectifier for 10kW output power, 800VDC output and 320V/400V/ 480V/530V (rms, line-to-line) mains voltage. These investigations finally lead to efficiency and component count figures. Furthermore, special attention is paid to the control of the whole three-phase system including the DC/DC converter output stages of the line-to-line modules of the A-Rectifier. Finally, topics of the continuation of the research are identified as, e.g., the realization of a prototype in order to verify the theoretical results experimentally also for unbalanced mains voltage conditions and with nonideal components such as nonlinear input inductors employing iron powder cores and the analysis of a A-Rectifier being formed by single-stage SEPIC-type line-to-line modules.

Evaluation of a delta-connection of three single-phase unity power factor rectifier modules (Δ-Rectifier) in comparison to a direct three-phase rectifier realization. Part II - component stress evaluation, efficiency, control

In this paper, a novel control concept for a unity power factor three-phase AC/DC two-stage telecommunications power supply system is proposed. The system is formed by an input-side delta-connection of three single-phase modules with parallel connected DC outputs. The control concept features output voltage control, module load sharing and mains voltage proportional guidance of the input currents and does allow to continue in operation also in case of heavily unbalanced mains voltage condition like those given for a missing mains phase or in case of an earth-fault of a mains phase or for a short circuit between two mains phases.

A novel control concept for operating a two-stage a-rectifier-based telecommunications power supply module under heavily unbalanced mains voltage conditions

R. Greul

Papers

Analysis and comparative evaluation of a three-phase three-level unity power factor y-rectifier

Evaluation of a delta-connection of three single-phase unity power factor rectifier modules (/spl Delta/-rectifier) in comparison to a direct three-phase rectifier realization

Evaluation of a delta-connection of three single-phase unity power factor rectifier modules (Δ-Rectifier) in comparison to a direct three-phase rectifier realization. Part II - component stress evaluation, efficiency, control

A novel control concept for operating a two-stage a-rectifier-based telecommunications power supply module under heavily unbalanced mains voltage conditions

Evaluation of a delta-connection of three single-phase unity power factor rectifier modules (Δ-Rectifier) in comparison to a direct three-phase rectifier realization. Part II - component stress evaluation, efficiency, control