Philipp Münch

Integrated current control, energy control and energy balancing of Modular Multilevel Converters

Modular Multilevel Converters (MMCs) are a new circuit topology to realize multilevel converters. Major advantages of MMCs in comparison to other multilevel converters or standard Voltage Source Converters (VSCs) are lower costs and a modular design for high voltage applications, higher reliability and longer maintenance intervals. However, modular multilevel topologies generally require advanced strategies for controlling and balancing energies since many energy storages are distributed all over the converter. This paper presents a novel integrated strategy for current control, energy control and energy balancing of MMCs. The MMC is modeled as a periodic bilinear time-varying system respecting all currents and energies. Furthermore, a control structure is proposed combining a periodic linear quadratic regulator (PLQR) with an extended and least squares (LS) estimator to determine the currents and energies. Finally, simulation results for converter energizing and transmission startup as well as a phase-to-ground fault are given to illustrate the effectiveness of the strategy.

Modeling and current control of modular multilevel converters considering actuator and sensor delays

Voltage source converter (VSC) technology becomes more and more common in high-voltage direct current (HVDC) transmission systems. Compared to conventional VSC technology modular multilevel design offers advantages such as higher voltage levels, modular construction, longer maintenance intervals and improved reliability. A multilevel approach can also help to reduce harmonics due to sinusoidal output voltages so that grid filters become dispensable. Modular multilevel converters (MMC) are a new circuit topology to realize multilevel converters that can be used for high-voltage transmission systems and offer the benefit of an only linearly rising hardware complexity for an increasing number of levels. To control the innovative MMC topology, special requirements exist which exceed classical converter control features. This paper presents a multivariable approach to realize an optimal current control considering actuator and sensor delays that occur in real converter control systems.

Multivariable current control of Modular Multilevel Converters with disturbance rejection and harmonics compensation

Voltage Source Converter (VSC) technology is very common in high-voltage direct current (HVDC) transmission systems. Compared to conventional VSC technology Modular Multilevel Converters (MMCs) offer advantages such as higher voltage levels, modular construction, longer maintenance intervals and improved reliability. For power transmission, stability, robustness of the control and especially the behavior during grid failures are important economic issues. Furthermore, compensation of harmonics can be an additional feature to improve the voltage quality of the connected grid. Regarding the innovative MMC topology, special control features are needed due to the higher number of control variables. This paper presents a multivariable control approach to realize an optimal current control of the positive, negative and zero phase-sequence converter currents without steady-state error and the compensation of higher harmonics using an extended estimator.

DEVELOPMENT PROCESS FOR DEPENDABLE HIGH-PERFORMANCE CONTROLLERS USING PETRI NETS AND FPGA TECHNOLOGY

Abstract A formal development process for logic controllers using Signal Interpreted Petri Nets and FPGA technology is presented. The development process covers all steps from design to implementation and is supported by the SIPN-Editor toolbox, a graphical editor that allows design, analysis and implementation of SIPN algorithms. As a new feature to increase dependability of logic controllers the SIPN-Editor toolbox supports export to VHDL language which allows implementation of SIPN algorithms on FPGA hardware. The implementation on FPGA is not only much faster than on an ordinary PLC hardware but also more dependable in several aspects. An algorithm to calculate a guaranteed response time is also given.

Energy Management for Hybrid Electric Tractors Combining Load Point Shifting, Regeneration and Boost

Political regulations to increase the fuel efficiency of vehicles are leading to hybrid electric vehicles offering more flexibility for operating the internal combustion engine and increasing the performance. In this paper an energy management for hybrid electric vehicles combining load point shifting based on optimization with regeneration and boost based on heuristics is introduced and the real-time implementation on a hybrid electric tractor is discussed. Simulation results indicate an increased fuel efficiency for transportation tasks.