Zdenek Peroutka

Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and √ s = 8 TeV by TOTEM

Abstract The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s = 8 TeV based on a high-statistics data sample obtained with the β ⁎ = 90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 | t | 0.2 GeV 2 with a significance greater than 7 σ . Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t = 0 , and further applying the optical theorem, yields total cross-section estimates of ( 101.5 ± 2.1 ) mb and ( 101.9 ± 2.1 ) mb , respectively, in agreement with previous TOTEM measurements.

Position-Based T-S Fuzzy Power Management for Tram With Energy Storage System

Energy storage systems (ESSs) play a significant role in performance improvement of future electric traction systems. This paper investigates an ESS based on supercapacitors for trams as a reliable technical solution with considerable energy saving potential. Operating the ESS onboard a tram brings the following benefits: reduction of peak power demands, decrease of power consumption, improvement of performance, and efficiency. Whereas the commonly used ESS power management (PM) has been dealing only with PM without vehicle position knowledge, the main emphasis of the presented research is put on position-based Takagi-Sugeno fuzzy (T-S fuzzy) PM for human-driven trams with an ESS. The tram position, located by, e.g., a Global Positioning System module, is used to predict future energy demands and power flows. This information is used in the preparation of the supercapacitor energy level and its power flow control. The optimal ESS power flow with respect to the tram position is a very complex problem. Therefore, soft computing techniques are used in this paper. The main part of the proposed ESS PM is the T-S fuzzy controller. The T-S fuzzy reduces problem dimensionality using expert knowledge represented by the rules. The output membership functions were optimized by differential evolution. The designed ESS PM was verified on real traffic data.

Robust Field Weakening Algorithm for Vector-Controlled Induction Machine Traction Drives

This paper focuses on the field weakening operation of the vector-controlled induction machine drive intended for traction application (trams and trolley-buses). New field weakening strategy based on the modulation depth control is presented. This strategy makes possible operation of the converter in the linear modulation area as well as in the overmodulation area (close to the six-step mode), even if the common carrier-based PWM is employed. The proposed algorithm is simple, independent of the machine parameter variations and provides maximum output torque. Very important contribution is that this method does not use feedback from the dc-link voltage. It significantly improves the immunity of the traction drive against the oscillations of the input dc-link filter. The simulation results presenting behaviour of the traction drive prototype of power of 160 kW and the performed on the laboratory prototype confirm the proper function of the proposed field weakening strategy

Single-phase current-source active rectifier for traction applications: new control strategy based on phase shift controller

This research has been motivated by industrial demand for single-phase current-source active rectifier (CSAR) dedicated for reconstruction of older types of dc machine locomotives operating on both ac catenary voltages of 25 kV/50 Hz and 15 kV/16 2/3 Hz. This contribution presents new control strategy of CSAR using controller of phase shift angle (phi) between trolley wire voltage and current. Regarding possible interaction with railway control signalling and due to the low switching frequency, the designed converter employs synchronous PWM. This paper describes in detail proposed converter control and presents simulation results of the laboratory prototype. The simulation results and theoretical conclusions are verified by experiments performed on designed low power laboratory prototype of traction CSAR with rated power of 7 kVA.

Control of traction single-phase current-source active rectifier under distorted power supply voltage

This research has been motivated by industrial demand for single-phase current-source active rectifier (CSAR) dedicated for reconstruction of older types of dc machine locomotives. This contribution presents new control strategy of CSAR using controller of phase shift angle (phi) between trolley wire voltage and current supplemented by compensation of trolley wire current waveform under supply voltage distortion. This control is able to keep the trolley wire current in demanded phase shift against supply voltage and preserve sinusoidal waveform of consumed current even under distorted trolley wire voltage. Simulation results and theoretical conclusions are verified on designed laboratory prototype of 7 kVA.

Design considerations for sensorless control of PMSM drive based on extended Kalman filter

This paper presents different structures of the extended Kalman filter (EKF) that can be employed in PMSM drives without either speed or position sensor. The contribution compares different machine models eligible for prediction step of EKF and discusses their benefits and drawbacks. In order to simplify the fixed-point implementation, specific simulation method is proposed. This method speed-ups control system prototyping and filter tuning under real conditions

Control of primary voltage source active rectifiers for traction converter with medium-frequency transformer

This paper deals with the new configuration of the traction converter with medium-frequency transformer intended for AC trolley wire fed locomotives. The main attention is paid to the primary serially connected single-phase voltage-source active rectifiers, which are directly connected to the trolley wire. This paper describes the control of the primary active rectifiers, presents simulation results as well as experimental evidence of designed low-voltage laboratory prototype of loco converter of rated power of 12 kW.

New field weakening strategy for AC machine drives for light traction vehicles

This paper presents new control strategy of vector-controlled ac machine traction drives intended for light traction vehicles in the field weakening region. Important contribution of the proposed field weakening method is improved drive immunity against oscillations of the input dc trolley wire filter, because our approach does not use the converter dc-link voltage feedback, as well as possible operation of the traction converter in the overmodulation (close to the six-step mode) with the conventional PWM. Theoretical conclusions and simulation results of both traction drive prototype and laboratory set-up are verified by experiments performed on the designed laboratory prototype of the induction machine trolley-bus drive. The proposed field weakening algorithm is in this paper generalized also for other control strategies - e.g. DTFC with constant switching frequency.

New generation of full low-floor trams: Control of wheel drives with permanent magnet synchronous motors

This paper presents a propulsion system concept for a new generation of full low-floor trams employing gearless wheel drives with surface-mounted permanent magnet synchronous motors (PMSM). The main attention is paid to the wheel drive control. The proposed control had to overcome two major problems: (i) oscillations of LC filters in traction converter dc-links, and (ii) load angle control due to required operation of PMSM with the load angle of 90° in order to fully utilize the PMSM capability. The drive operation in a very wide speed range in a field weakening and specifically the load angle limitation was a new problem for which we did not find any reference related to traction applications. Proper function of presented propulsion system and its control is verified by simulations of the tram drive prototype and by experiments made on both a small-scale wheel drive prototype of 10.7kW and developed tram ŠkODA ForCity.

Compensation of low-frequency disturbances for traction converter with medium-frequency transformer for multi-system suburban units

The presented research deals with a new configuration of a main traction converter with medium-frequency transformer which is intended for modern multisystem suburban units and locomotives. This paper exactly introduces proposed control of primary voltage source active rectifiers with direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. The theoretical conclusions are verified by simulations and experiments made on developed small-scale laboratory prototype of traction converter of rated power of 12kW.