The yields of (anti-)protons were measured by the NA49 Collaboration in centrality selected Pb+Pb collisions at 40A GeV and 158A GeV. Particle identification was obtained in the laboratory momentum range from 5 to 63 GeV/c by measuring the energy loss dE/dx in the TPC detector gas. The corresponding rapidity coverage extends 1.6 units from midrapidity into the forward hemisphere. Transverse mass spectra, the rapidity dependences of the average transverse mass, and rapidity density distributions were studied as a function of collision centrality. The values of the average transverse mass as well as the midrapidity yields of protons normalized to the number of wounded nucleons show only modest centrality dependences. In contrast, the shape of the rapidity distribution changes significantly with collision centrality, especially at 40A GeV. The experimental results are compared to calculations of the HSD and UrQMD transport models.

Results on ,¯ , − , and¯ + production in central Pb+Pb reactions at 20A, 30A, 40A, 80A, and 158A GeV are presented. The energy dependence of transverse mass spectra, rapidity spectra, and multiplicities is discussed. Comparisons to string hadronic models (UrQMD and HSD) and statistical hadron gas models are shown. Although the latter provide a reasonable description of all particle yields, the first class of models fails to match the − and¯ + multiplicities.

Kaons and protons carry large parts of two conserved quantities, strangeness and baryon number.It is argued that their correlation and thus also fluctuations are sensitive to conditions prevailing at the anticipated parton-hadron phase boundary. Fluctuations of the (K + +K − )/(p+ p) and K + /p ratios have been measured for the first time by NA49 in central Pb+Pb collisions at 5 SPS energies between √ s NN = 6.3 GeV and 17.3 GeV. Both ratios exhibit a change of sign in σ dyn , a measure of non-statistical fluctuations, around √ s NN = 8 GeV. Below this energy, σ dyn is positive, indicating higher fluctuation compared to a mixed event background sample, while for higher energies, σ dyn is negative, indicating correlated emission of kaons and protons. The results are compared to hadronic transport model calculations which fail to reproduce the energy dependence.

The auxiliary submodule power supply is a vital component of a modular multilevel converter submodule or any multi-submodule converter. Considering the high isolation requirements and difficulties to provide power from the ground potential, the auxiliary submodule power supply must be simple, work reliably and not compromise the submodule's reliability. A flyback supply from the submodule's dc link with multiple sets of isolated secondary windings solves at once the low-voltage generation and the required voltage isolation for semiconductor gate circuits and protection without need for an externally supplied lowvoltage input to the submodule (high-isolation connection). This paper presents an isolated, flyback-based auxiliary submodule power supply with planar magnetic, printed circuit board integrated windings and multiple isolated outputs for a medium voltage modular multilevel converter as well as detailed electrical and magnetic mathematical modelling, technological integration challenges description and proper experimental test considerations. Index Terms-Auxiliary submodule power supply (ASPS), flyback, modular multilevel converter (MMC), planar transformer. NOMENCLATURE V sm Submodule voltage. L p Flyback transformer primary inductance. I p Primary peak current. D Duty cycle. f sw Switching frequency. N Turns number. μ 0 Permeability in vacuum. μ r Relative permeability.  Magnetic reluctance. l ag Air-gap length. V DS Drain to source voltage. V L Voltage spike due to the leakage inductance. V D Rectifier diode forward voltage drop. R load,eq Equivalent load resistance. C out,eq Equivalent output capacitance. R ESR Equivalent series resistance.

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios (K, and (K + + K − )/(p +p) are presented for Pb + Pb collisions at 158A GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure σ dyn , increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the (KA description of the centrality and energy dependence of (K + + K − )/(p +p) ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.

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