Daniel Siemaszko

Klystron modulator technology challenges for the Compact Linear Collider (CLIC)

This paper presents the research and development challenges foreseen for the klystron modulators design for a new accelerator complex, the Compact Linear Collider (CLIC). This huge electron-positron accelerator needs roughly 300MW of average power for feeding the 1638 required klystron modulators. The main challenges for designing theses new pulsed klystron modulators are described. Considering the state of the art in several domain such as converters topologies, voltage measurements precision, pulse-to-pulse reproducibility, AC power quality issues, efficiency maximization, accelerator reliability & availability, this paper illustrates the most challenging future developments directions and the need for an international and coordinated R&D program.

Implementation and experimental set-up of a Modular Multilevel Converter in a Multi Terminal DC/AC transmission network

In this paper the realization of a Multi Terminal DC pilot is presented. For the interaction with the medium voltage AC grid, a Modular Multilevel Converter has been designed for its features in low harmonic content, scalability, and flexibility. The Energy buffering of the converter will allow the converter to sustain either AC or DC grids. The operation of the converter is simulated together with the first experimental results of the implementation.

Design of a modular resonant converter for 25kV-8A DC power supply of RF cavities

This paper describes the design of an LCC resonant tank that is to be used in a 300kW modular power converter for an application in particle accelerators. The aim of the power supply is to provide a so-called RF cavity with 25kV DC and a current up to 8A. Modular approach is chosen for redundancy and availability. Each module is composed of a resonant tank with a step-up Medium Frequency Transformer with its secondary windings put is series. Full gain is ensured in the full operation frequency range considering component value inaccuracies and ageing of capacitors. The paper focusses on the design of the resonant tank and its implementation in a 100kW power module prototype.

Double frame control and power compensation for power converters connected to weak networks with disturbances

CERN is studying the implementation of high power active front ends, implying the operation of a voltage source inverters connected to a grid that can be considered as weak when compared to the converter nominal power. Proper synchronisation is a key point for current control stability. The handling of networks with asymmetric disturbances implies the accurate handling of the second harmonic component appearing under unbalanced networks by the proper decoupling of the positive and negative sequence of the network voltages and currents. The use of a double frame controller allow the full control of phase current symmetry or the compensation instantaneous active power oscillation.

Impact of Modularity and Redundancy in Optimising the Reliability of Power Systems that Include a Large Number of Power Converters

Abstract CERN is working on a new particle accelerator that will require a very large number of power converters. In that view, the reliability of the whole powering will be a major issue. The use of a redundancy and modularity may help increasing the overall machine availability. However, the reliability of the redundancy system must be high enough to add a significant improvement when compared to simple module systems. This paper suggests a comparative study of several modular and redundant configurations for optimising power converters reliability and draws some conclusion from what has been achieved in the LHC previous experience.

Design and implementation of a multi-dsp based digital control system architecture for modular multilevel converters

This paper presents the design and implementation of a digital control system for modular multilevel converters, based on digital signal processors. To achieve higher system control reliability and multi-functionality, the proposed architecture has been built with an effective split of the control tasks involved between a master controller and six slave controllers, one for each of the six arms of the converter. The master controller handles energy flow within the converter and user communication using Ethernet and universal serial bus. Each slave controller handles capacitors voltages balancing within the arm. Intercommunication between the different boards is achieved mainly through optical fiber and inter-integrated circuit bus. Experiments have been carried out to verify the effectiveness of this architecture.

Modular resonant converter for 25kV-8A power supply: Design, implementation and real time simulation

This paper describes the design of a 300kW modular resonant power converter for an application in particle accelerators. The aim of the power supply is to provide a so-called RF cavity with 25kV DC voltage and a current up to 8A. Modular approach is chosen for redundancy and availability. Each module is composed of a resonant tank with a step-up MF transformer with its secondary windings put is series for reaching higher voltages. Full gain is ensured in the full operation frequency range considering component value inaccuracies and ageing of capacitors. The design of the resonant tank is detailed with its dimensioning and integration issues. Hardware in the loop validation of two control methods is done on one 100kW module to prepare experimental validation of a single module before implementing the full system.