Analytical switching loss model for superjunction MOSFET with capacitive nonlinearities and displacement currents for DC-DC power converters

A new analytical model is presented in this study to predict power losses and waveforms of high-voltage silicon superjunction MOSFET during hard-switching operation. This model depends on datasheet parameters of the semiconductors, as well as the parasitics obtained from the printed circuit board characterization. It is important to note that it also includes original features accounting for strong capacitive nonlinearities and displacement currents. Moreover, these features demand unusual extraction of electrical characteristics from regular datasheets. A detailed analysis on how to obtain this electrical characteristic is included in this study. Finally, the high accuracy of the model is validated with experimental measurements in a double-pulse buck converter setup by using commercial SJ MOSFET, as well as advanced device prototypes under development.This work was supported by the Asturian Gobernment through the grant Beca Predoctoral “Severo Ochoa” BP14–140. This work was also supported by the project E2 SG, cofunded by grants from Belgium, Italy, Austria, Germany, Spain, The Netherlands, Portugal, Slovakia, The U.K., and the ECSEL

State estimation in distribution grids

State estimation in distribution grids Gelagaev, R. Vermeyen, P. Driesen, J. ELECTA ESAT, Leuven; This paper appears in: Harmonics and Quality of Power, 2008. ICHQP 2008. 13th International Conference on Publication Date: Sept. 28 2008-Oct. 1 2008 On page(s): 1-6 ISBN: 978-1-4244-1771-1 INSPEC Accession Number: 10389882 Digital Object Identifier: 10.1109/ICHQP.2008.4668803 Current Version Published: 2008-11-07 Abstract Problems and techniques for estimating the state of an observable distribution grid are investigated. A distribution grid is observable if the state of the grid can be fully determined. For the simulations, the modified 34-bus IEEE test feeder is used. The measurements needed for the state estimation are generated by the ladder iterative technique. Two methods for the state estimation are analyzed: weighted least squares and extended Kalman filter. Both estimators try to find the most probable state based on the available measurements. The result is that the Kalman filter mostly needs less iterations and calculation time. The disadvantage of the Kalman filter is that it needs some foreknowlegde about the state.status: publishe

Numerical Observability Analysis of Distribution Systems

Abstract—Observability analysis is a very important tool in state estimation. For a given set of measurements and their geographical location in the system, it determines whether the state of the whole system can be estimated. In this paper a numerical observability analysis, applicable to distribution systems is discussed and applied to the IEEE 34 bus test feeder. The method is based on the inverse function theory and the Jacobian matrix of the system. By calculating the dependent columns of the Jacobian matrix it is possible to determine the unobservable branches in the system. This also gives an indication of how many linearly independent pseudo-measurements are required to make the distribution system observable. Because the R=X ratio is not negligible in the distribution lines, a transformation has been used to simplify the observability analysis.status: publishe

A Novel Voltage Clamp Circuit for the Measurement of Transistor Dynamic On-Resistance

For determining the dynamic on-resistance Rdynon of a power transistor, the voltage and current waveforms have to be measured during the switching operation. In measurements of voltage waveforms, using an oscilloscope, the characteristics of an amplifier inside the oscilloscope are distorted when the range of the measurement channel is not set wide enough to measure both on-state and off-state voltage, resulting in failure to accurately measure the voltage waveforms. A novel voltage clamp circuit improving the accuracy of the transistor on-state voltage measurement is presented. The measurement accuracy is improved by clamping the off-state voltage across the transistor to a lower voltage that is still greater than the on-state voltage. Unlike traditional clamping circuit, the presented voltage clamp circuit does not introduce delay caused by RC time constants keeping the voltage waveform clear even during state transitions of the evaluated semiconductor device for frequencies up to 1MHz.status: publishe

An Electromagnetic Circuit Simulator For Power Electronics

With the upcoming of wide bandgap semiconductors, transistors in power electronics can be used with higher switching frequencies, up to several tens of megahertzes. In the rising and falling edges of the pulse generated by transistors even higher frequencies are present. At these frequencies the conductors in the circuits will act as transmission lines. This means reflections can occur in case of poor impedance matching which can double the voltages across the electrical components. Also energy will be lost due to radiation. This radiation can interact with neighbouring circuits. Therefore classical circuit solvers like SPICE cannot simulate these circuits accurately at high switching frequencies. A method for solving the full equations of Maxwell for circuits with discrete non-linear, non-ideal elements is presented. To this end the method of moments is used in combination with a classical circuit simulator. Both operate in the frequency domain. A few methods to greatly accelerate the calculations are also presented. The methods are implemented and tested in Matlab®.status: publishe

Accurately modelling of parasitics in power electronics circuits using an easy RLC-extraction method

A method for accurately modelling parasitics in power electronic circuits, is presented in this paper. The freeware software programs FastCap and FastHenry are used to create a model of the printed circuit board tracks, consisting of resistances, self and mutual inductances, and self and mutual capacitances. This model can be easily loaded into a standard circuit simulator such as Spice, together with models for other components, such as the diodes, transistors, coils and capacitances. Thus, the power electronic circuit can easily be simulated in the time domain, returning electrical currents and voltages typically being subject to ringing effects and overshoot.status: publishe