Fujitsu Corporation

Fujtsu Denso Limited

Shinichi Otsu

Makoto Mukai

Hiroshi Shimamori

Shigeharu Yamashita

Kazutoshi Fuchigami

Sentarou Tokimi

In calculating an electromagnetic field intensity by a moment method, real and imaginary parts of a mutual impedance, mutual admittance, and mutual reaction between elements and of the elements themselves are approximated by a sum of terms each with a frequency raised to a power. The mutual impedances, etc. at a plurality of sample frequencies are calculated using known mathematical equations, and simultaneous equations obtained by substituting the sample frequencies and the mutual impedances at the respective sample frequencies into an approximate equation are solved to calculate approximation coefficients for the approximate equation. Using the thus obtained approximate equations, the mutual impedance, etc. at a designated frequency are calculated, and substituted into simultaneous equations describing a boundary condition for each element; by solving the simultaneous equations, the electric current, equivalent electric current, and equivalent magnetic current of each element are calculated, from which the electromagnetic field intensity is calculated.

Calculation of electromagnetic field intensity by moment method

A simulation apparatus, using the moment method and at high speed, simulates the intensity of an electromagnetic field, etc. of a time domain. A transforming unit obtains a frequency spectrum by segmenting time series data of a wave source and applying a Fourier transform thereto. A calculating unit calculates the mutual impedance at a sampling frequency, generates an approximate expression of the mutual impedance from the calculated mutual impedance and the sampling frequency and calculates the mutual impedance at respective frequencies obtained by the transforming unit by using the generated approximate expression. A simulating unit finds a current spectrum flowing in each element, according to the moment method, from the mutual impedance calculated by the calculating unit and the frequency spectrum obtained by the transforming unit and finds the spectrum of a voltage, an electric field, and a magnetic field from the found current spectrum. An inverse transforming unit applies an inverse Fourier transform to the spectra found by the simulating unit and outputs the result.

Simulation apparatus and simulation method for electromagnetic field

Disclosed is a synchronous rectifier type DC-to-DC converter capable of preventing an increase in losses occurring when a rectifier synchronous rectification switch and a flywheel synchronous rectification switch, which are responsible for rectification on the side of a secondary winding of a transformer, are turned on simultaneously, and the destruction of FETs or windings due to large currents. The DC-to-DC converter comprises a transformer, a primary switching device connected in series with a primary winding of the transformer, a control circuit for controlling turning on or off of the primary switching device, a rectifier synchronous rectification switching device, and a flywheel synchronous rectification switching device, and converts a voltage of a DC power source into another voltage. The DC-to-DC converter further comprises a rectifier rise delay inductive device connected in series with the rectifier synchronous rectification switching device and a flywheel rise delay inductive device connected in series with the flywheel synchronous rectification switching device.

Growing community of inventors

Kawasaki, Japan

Shinichi Otsu