State-space average modelling of converters with parasitics and storage-time modulation

The State-Space Averaging approach to modelling switching converter power stages is used to extend the analytical descriptions of the buck, boost, buck-boost, and Cuk converters to included the effects of all parasitic resistances and transistor storage-time modulation. The analysis reveals for the first time a new and unexpected term in the line to ouput response of the Cuk converter. The new term contains a right half-plane zero produced by the energy transfer capacitance in combination with the duty-ratio-weighted sum of the on-resistances of the transistor and diode plus a non-dissipative ac resistance term due to transistor storage-time modulation. The conventional circuit model of the converter is modified to include the effects of the new term. The improved model permits an eas physical interpretation of the new zero, which has been observed only the in Cuk converter. An extended analysis of storage-time modulation in bipolar transistor switches shows that the ac small-signal performance of a switching converter is highly dependent on the nature of the base drive. It is demonstrated that storage-time modulation in conjunction with a proportional base drive can produce instability in switching converters, even open-loop. The results of these analyses are verified experimentally and their impacts on practical converters are discussed

Microprocessor-Controlled Digital Shunt Regulator

A new approach to the design of power systems is presented in which a microprocessor is used as a controller for a digital shunt regulator (DSR). This approach meets the demands of future space and ground missions, i.e., high efficiency, high reliability, low weight, low volume, increased flexibility, and less development time. This approach responds to future demands by permitting real-time modification of system parameters for system optimization. This feature is especially important in the event of an anomaly. As the microprocessor need not be dedicated to the DSR, it can simultaneously be used for battery management and for charge regulator/discharge regulator control. This approach also reduces the component count, simplifies assembly and testing of the unit, results in significant time saving, and increases the reliability

Tests of the Equivalence Principle with Neutral Kaons

We test the Principle of Equivalence for particles and antiparticles, using CPLEAR data on tagged K0 and K0bar decays into pi^+ pi^-. For the first time, we search for possible annual, monthly and diurnal modulations of the observables |eta_{+-}| and phi_{+-}, that could be correlated with variations in astrophysical potentials. Within the accuracy of CPLEAR, the measured values of |eta_{+-}| and phi_{+-} are found not to be correlated with changes of the gravitational potential. We analyze data assuming effective scalar, vector and tensor interactions, and we conclude that the Principle of Equivalence between particles and antiparticles holds to a level of 6.5, 4.3 and 1.8 x 10^{-9}, respectively, for scalar, vector and tensor potentials originating from the Sun with a range much greater than the distance Earth-Sun. We also study energy-dependent effects that might arise from vector or tensor interactions. Finally, we compile upper limits on the gravitational coupling difference between K0 and K0bar as a function of the scalar, vector and tensor interaction range.Comment: 15 pages latex 2e, five figures, one style file (cernart.csl) incorporate

Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR

We use fits to recent published CPLEAR data on neutral kaon decays to $\pi^+\pi^-$ and $\pi e\nu$ to constrain the CPT--violation parameters appearing in a formulation of the neutral kaon system as an open quantum-mechanical system. The obtained upper limits of the CPT--violation parameters are approaching the range suggested by certain ideas concerning quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures