Joan Bergas-Jané

Design and Control of a Modular Multilevel DC/DC Converter for Regenerative Applications

This paper compares different cascaded and multilevel topologies to interface supercapacitors to a dc bus in regenerative braking applications. It is shown that the modular multilevel dc/dc converter (MMC) can benefit from both reduced voltage and increased frequency across the inductor to reduce its weight and volume when using phase shifting modulation. The proposed control method is able to balance supercapacitor voltage while providing precise output current control. The converter topology and control method are validated with simulations and experimental results.

Control of a Wind Farm Based on Synchronous Generators With a Central HVDC-VSC Converter

A control scheme for wind farms based on synchronous generators connected to a single power converter is presented. The scheme is applicable to HVDC interfaced offshore or remote wind farms. The proposed control scheme is based on computing the optimal wind farm electrical frequency depending on the different incoming wind speeds. The power converter regulates the system frequency by adjusting the power injected to the HVDC circuit. Fault ride-through is also possible by reducing rapidly the injected active power. The proposed scheme is validated by means of simulations with a wind farm composed of four wind turbines.

High-Accuracy All-Digital Resolver-to-Digital Conversion

In this paper, a high-accuracy all-digital resolverto-digital (R/D) converter is presented. The two basic components of a conventional tracking R/D converter, the phase detector and the loop filter, are software implemented by frequency-shifting techniques and a decoupled double synchronous reference frame-based phase-locked loop (DSRF-PLL). This PLL allows the simultaneous extraction of the angular position and speed of the rotatory resolver, even in the presence of gain and phase errors in the resolver. In order to increase accuracy and to minimize the time lag of the whole system, oversampling methods and downsampling finite-impulse response digital filters are introduced. Finally, DSP implementation issues, like the use of techniques to synchronize the resolver output signals with the excitation one, are discussed. Using these combined techniques and a standard DSP with a 12-bit analog-to-digital converter, resolutions of up to 14 bits can be achieved with a computation cost of about 13% of the total (100 MIPs). The paper presents the main techniques, simulation, and experimental results.

Permanent magnet synchronous generator offshore wind farms connected to a single power converter

The paper deals with permanent magnet synchronous generators based wind farms connected to a single power HVDC-VSC converter. A control scheme is proposed and validated by means of simulations. The proposed control scheme needs only current and voltage measurements in the wind farm transformer and seeks the maximum power generation using a variable frequency offshore grid, provided by the HVDC-VSC. The work includes an evaluation of the power generated by variable and constant frequency offshore wind farms. Results show that a significant power increase of more than 20 % can be obtained by applying the appropriate variable frequency in a certain wind farm. The case study considers a wind farm composed of four wind turbines based on permanent magnet synchronous generators.

Design and control of a half-bridge converter to drive piezoelectric actuators

The present work deals with the development and control of a converter to drive piezoelectric actuators. Due to the piezoelectric load specification, a half-bridge converter is proposed. Such a converter is analyzed considering charging and discharging modes. The converter is controlled by means of a sliding mode control strategy, employing two different sliding surfaces for the charging and discharging operation mode. The proposed scheme is validated by means of simulations.

Assessment of impact of charging infrastructure for electric vehicles on distribution networks

Charging infrastructure for electric vehicles can impact significantly on distribution systems. Normal charging will be the usual way while fast charging has to be considered as a complement to this. Both charging processes represent a new load for distribution networks. The effect of both normal and fast charging are assesses. Management strategies are proposed for reducing the impact and the results are presented.

All-digital DSP-based phase-locked loop for induction heating applications

Phase-locked loop schemes are widely used in induction heating applications for controlling the converters. Most authors use total or partial analog solutions to implement the control schemes, which are less sturdy and flexible to changes than digital schemes. In this paper, an all-digital DSP-based PLL is presented. It has fewer variations due to the tolerances of the analog components and provides great flexibility in a wide range of conditions just by reprogramming. Moreover, it allows changing dynamically some of the parameters during the process and opens up the possibility of more complex control algorithms. The all-digital PLL has been simulated and experimentally tested, demonstrating the feasibility and reliability of this type of control in a real industrial equipment

Simulation of an induction hardening system during Curie temperature transition considering converter's performance

Purpose – The aim of this paper is to simulate, test and evaluate an induction heating process considering the converters performance.Design/methodology/approach – In case of continuous induction hardening processes, the load changes abruptly during the transition to Curie temperature, becoming significant considering the converters behavior. In this paper, an induction heating system is simulated combining the numerical analysis of the electromagnetic‐thermal and electrical problem, focusing mainly on the converters performance. The simulations are realized by using commercial FEM software and the voltage and the frequency are manually varied according to the converters control. The system has also been implemented in an experimental setup and the results obtained have been compared with the simulations.Findings – The importance of considering the converters dynamics was observed during the simulations. The simulation results showed a correspondence with the experimental results, validating the simu...

Miller Effect to Drive a Piezoelectric Actuator

Abstract This paper presents the intentional use of the Miller effect present in MOSFET devices to control a piezoelectric actuator. The Miller effect, normally neglected or minimized, can be useful to meet the dv/dt application requirements. A half-bridge converter is used as a power amplifier, where an external R-C network has been added to achieve the desired dv/dt. The transient semiconductor device behavior is simulated and tested experimentally.