Luciano Schuch

Analysis and Design of a New High-Efficiency Bidirectional Integrated ZVT PWM Converter for DC-Bus and Battery-Bank Interface

This paper proposes a high-efficiency bidirectional integrated zero-voltage transition (iZVT) pulsewidth-modulation (PWM) converter for dc-bus and battery-bank interface. The proposed converter can operate as battery charger when the utility is within its acceptable voltage range and can supply energy to critical loads when the utility fails. The converter practically eliminates both low- and high-frequency current ripple on the batteries, thus maximizing battery life without penalizing the volume of the converter. Moreover, soft switching of all switches is achieved using the proposed integrated auxiliary commutation circuit (iACC). Just one iACC is used to provide soft-switching conditions for the three converters that compose the system: the preregulator (boost), the battery charger (bidirectional converter operating as a buck), and the backup converter (bidirectional converter operating as a boost). This auxiliary circuit has few components and low reactive energy, increasing the systems overall efficiency. Experimental results based on a 580-W prototype are presented to validate the analysis and the proposed design procedure and to demonstrate the performance of the proposed approach

LMI-Based Control for Grid-Connected Converters With LCL Filters Under Uncertain Parameters

This paper presents a linear matrix inequality-based procedure for the design of state feedback current controllers that are robust to uncertainties on grid inductance for grid-connected converters with LCL filters. The state feedback control law includes the filter state variables, the states of resonant controllers, and considers also the delay from digital control implementation. As the main contribution here, the proposed strategy allows to deal with resonant controllers of arbitrary dimension, and provides results complying with IEEE Standard 1547 requirements. The control synthesis condition takes into account the assignment of the closed-loop eigenvalues in a circular region with radius r, located inside the unit circle, and the control design relies only on the choice of the value of the radius in the interval 0 <; r ≤ 1, providing all the state feedback gains in a simple and efficient procedure.

Integrated ZVT auxiliary commutation circuit for input stage of double-conversion UPSs

This paper proposes an integrated zero voltage transition (ZVT) auxiliary commutation circuit applied to a universal input ac/dc system with a bidirectional converter for dc bus and battery bank interface. With the bidirectional converter it is possible to reduce the cost of the battery bank and virtually eliminate both low and high frequency current ripple in the batteries. An integrated ZVT auxiliary commutation circuit has been included to the system to achieve ZVT commutation at the main switches in all operation modes. In addition, this auxiliary commutation circuit controls the di/dt of the resonant process, allowing the utilization of slow diodes [intrinsic diodes of metal oxide semiconductor field effect transistors (MOSFETs)] in the bidirectional converter and, therefore, reducing the overall system cost. Integrated commutation circuit is based on a new concept in which the energy involved in one or more commutation processes is utilized to assist another commutation processes. Moreover, a control system has been developed and analyzed for the correct operation of the proposed system. Experimental results based on a 580-W prototype are presented to demonstrate the good performance of the proposed system.

Synthesis Methodology for Multi-Pole ZVT Converters

This paper proposes a novel synthesis methodology to generate integrated ZVT topologies, as well to systematize the topologies already known. It is presented an approach to classify the single pole ZVT converters. This approach can be expanded to multi-pole systems, such as poly-phase inverters and rectifiers. Uninterruptible Power Supplies and Variable-Speed Drives. The connections among several topologies presented so far are easily seen by means of the general diagrams shown in this paper. The analysis and understanding of advantages, disadvantages, merits and limitations of each converter is made easier since these converters are obtained from a common approach presented in this paper.

EMI investigation yield by single-phase PFC pre-regulators

This paper investigates the problem of electromagnetic interference (EMI) generated into power converters used to correct the power factor (PFC). The topologies discussed in this paper are the boost converter, interleaved boost and dual boost. The paths traveled by differential mode (DM) noise and common mode (CM) noise are illustrated. An analysis of the inductor parasitic capacitance impact over the conducted noise is realized. All converters were designed in a way that the total harmonic distortion (THD) of the input current be the same, in order to use the same input filter. The EMI filter designed to comply with the EMI standards and experimental results with filter are also shown.

Capability analysis of a D-STATCOM integrated to a single-phase to three-phase converter for rural grids

This paper presents a capability study of a static converter system to provide balanced three-phase four-wire with grounded neutral from single-phase network. The system is connected in parallel with the single-phase grid, that matches one of the output three-phase terminal. The converter absorbs active power from single phase grid to produce two additional phases of the three-phase system. Furthermore, it allows the voltage compensation or power factor correction through reactive power injection. This system also allows the connection of alternative sources to DC bus.

DAB Converter Modeling and Control Applied to Charging Batteries

Photovoltaic systems are assuming an important role in the integration of renewable sources in the energy generation. The number of connections of this type of generation has grown considerably in recent years, bringing with it problems such as varying voltage, current, power and frequency levels at points with a large number of connections. Therefore, in order to maintain these levels within acceptable ranges and since it is a source that has an intermittent characteristic, it is necessary to integrate a system of energy storage (batteries, for example) for the best use of the generated energy. For the connection of the generation system to the battery bank it becomes necessary to use a DC-DC converter with high voltage gain, bidirectionality in the power flow and galvanic isolation. In this work, the Dual Active Bridge (DAB) converter with topological modification in the output is used, and the mathematical modeling of the converter is performed through two methods: the generalized average model and the linearization of the output current. In addition, a comparative analysis between the methods is performed and the Artigo submetido em 27/11/2017. Primeira revisão em 13/02/2018. Aceito para publicação em 17/04/2018 por recomendação do Editor Marcello Mezaroba. design of a current controller for the DAB is developed. Finally, the experimental results are presented. 

Smart distribution transformer for secondary voltage regulation and load modeling

The distribution networks have been subjected to increased demand for electricity and the inclusion of distributed generation (DG), which have affected the voltage regulation. In this work, it is proposed a smart distribution transformer, which encompasses an electronic on-load tap changer and a communication system. In addition to the automatic or remote voltage regulation, the system enables to identify the load model at the interface between primary and secondary distribution systems. These characteristics permit the enhancement of the power quality, along with the improvement of the distribution system operation, planning and revenue management. The main focus of this work is the load parameter identification, which is validated by a simulation tool and experimental results.

Methodology for product design of photovoltaic inverters

This paper proposes a methodology for product design and comparison of photovoltaic inverters circuitry. This methodology compares costs and power losses of two different circuit solutions, using a reference value for the cost of power of photovoltaic system. Power losses for each circuit solutions are calculated similarly to the weighted efficiencies like European, Californian, and Brazilian, in order to obtain a site-dependent power electronics design. This methodology can be applied to compare different circuit solutions and also different inverter topologies. A design example of the dc bus capacitor of a PV inverter is presented do demonstrate the proposed methodology.