Nowadays, switching power supplies are used in almost all electronic devices to regulate the voltage amplitude. The only obstacle on using these devices is the production of high frequency harmonics that violates diff...Nowadays, switching power supplies are used in almost all electronic devices to regulate the voltage amplitude. The only obstacle on using these devices is the production of high frequency harmonics that violates different standards such as （FCC, VDE, 461 ）. In this paper the sources of various noises in switching power supplies will be introduced. Then, using appropriate model for high frequency transformers, a sample switching power supply will be simulated. In this simulation, the effect of leakage inductance on current and voltage waveforms of the input and output switches, which are the main cause of common mode differential mode noises and radiations, will be discussed and harmonically analyzed. Finally the experimental results will confirm the simulation conclusions.展开更多
The motion of a particle on a screen is directly affected by the motion of the screen if airflow and inter- granular friction are ignored. To study this effect, a mathematical model was established to analyze the moti...The motion of a particle on a screen is directly affected by the motion of the screen if airflow and inter- granular friction are ignored. To study this effect, a mathematical model was established to analyze the motion of a planar reciprocating vibrating screen, and a matrix method was employed to derive its equa- tion of motion. The motion of the screen was simulated numerically and analyzed using MATLAB. The results show that the screen undergoes non-simple harmonic motion and the law of motion of each point in the screen is different. The tilt angle of the screen during screening is not constant but varies according to a specific periodic function. The results of numerical simulations were verified through experiments. A high-speed camera was used to track the motion of three points in the longitudinal direction of the screen. The balance equation for forces acting on a single particle on the screen was derived based on the non-simple harmonic motion of the screen, These forces were simulated using MATLAB. Different types of particle motion like slipping forward, moving backward, and being tossed to different parts of the screen were analyzed. A vibro-impact motion model for a particle on the non-simple harmonic vibrating screen was established based on the nonlinear law of motion of the particle. The stability of fixed points of the map is discussed. Regimes of different particle behaviors such as stable periodic motion, period-doubling bifurcation motion, Hopf bifurcation motion, and chaotic motion were obtained. With the actual law of motion of the screen and the behavior of a particle on the screen, a theoretical basis for design optimization of the screen is provided.展开更多
文摘Nowadays, switching power supplies are used in almost all electronic devices to regulate the voltage amplitude. The only obstacle on using these devices is the production of high frequency harmonics that violates different standards such as （FCC, VDE, 461 ）. In this paper the sources of various noises in switching power supplies will be introduced. Then, using appropriate model for high frequency transformers, a sample switching power supply will be simulated. In this simulation, the effect of leakage inductance on current and voltage waveforms of the input and output switches, which are the main cause of common mode differential mode noises and radiations, will be discussed and harmonically analyzed. Finally the experimental results will confirm the simulation conclusions.
基金This work was financially supported by the Chinese Natural Science Foundation （Grant No. 51475090）, New Century Excel- lent Talents of General Universities of Heilongjiang Province, China （Grant No. 1254-NCET-003） and Youth Science and Technology Innovation Fund of Harbin City, China （Grant No. 2014RFQXJ142）, and Science Backbone Project of the Northeast Agricultural University.
文摘The motion of a particle on a screen is directly affected by the motion of the screen if airflow and inter- granular friction are ignored. To study this effect, a mathematical model was established to analyze the motion of a planar reciprocating vibrating screen, and a matrix method was employed to derive its equa- tion of motion. The motion of the screen was simulated numerically and analyzed using MATLAB. The results show that the screen undergoes non-simple harmonic motion and the law of motion of each point in the screen is different. The tilt angle of the screen during screening is not constant but varies according to a specific periodic function. The results of numerical simulations were verified through experiments. A high-speed camera was used to track the motion of three points in the longitudinal direction of the screen. The balance equation for forces acting on a single particle on the screen was derived based on the non-simple harmonic motion of the screen, These forces were simulated using MATLAB. Different types of particle motion like slipping forward, moving backward, and being tossed to different parts of the screen were analyzed. A vibro-impact motion model for a particle on the non-simple harmonic vibrating screen was established based on the nonlinear law of motion of the particle. The stability of fixed points of the map is discussed. Regimes of different particle behaviors such as stable periodic motion, period-doubling bifurcation motion, Hopf bifurcation motion, and chaotic motion were obtained. With the actual law of motion of the screen and the behavior of a particle on the screen, a theoretical basis for design optimization of the screen is provided.
