Zero vectors are randomized with the sample frequency and the average switching frequency equals to sample frequency with some constraint.

Simulation and mean frequency estimation on ultrasound seawater flow signals;

Several mean frequency estimation methods for Doppler ultrasound signals have been introduced in this paper,then a new mean frequency estimation method based on Teager algorithm is proposed.

<Abstrcat>From molecular beam s speed distribution function,molecular beam s frequency distribution function is deduced,and calculates mean frequency,root-mean-square frequency and most possible frequency are calculated,and compared with corresponding characteristic quantities of speed distribution function one by one,and their physical significance are explaned.

Complex correlation method for estimating average frequency of signal is introduced in this paper.

Selection of switch frequency in direct current electromotor PWM modulation.;

The DC-DC convertor features high switch frequency up to 1MHz using ultra-small inductors and ceramic capacitors.

The reason of output current distortion is analyzed;and a new way to resolve the problem is put forward;it is controlling switch frequency changing in different sections according to system run state.

Selection of phase-shift SPWM switching frequency

Hysteresis control has disadvantage of unstable switching frequency.

To reduce the switching frequency and current error of a static synchronous compensator (STATCOM) for reactive power compensation, a novel direct current control strategy is proposed.

For solving the cross-coupling problem caused by low switching frequency a new closed-loop variable speed control system which is based on flux trajectory control and different from vector control was introduced.