Total harmonic distortion (THD) is one of the key technical indexes of inverter output voltage. Optimization o f switching points and filter parameters could ensure the switching-point-preset sinusoidal pulse width mo...Total harmonic distortion (THD) is one of the key technical indexes of inverter output voltage. Optimization o f switching points and filter parameters could ensure the switching-point-preset sinusoidal pulse width modulation (SPWM) inverters with low harmonyic content in theory.The THD value would be increased by switching time delay of power devices and control circuit. A new control coecuit with delay time compensation is presented in this paper. With this control scheme, the output of the inverter could be basically identified with the theory given.Test results of experimental circuit verify that the control circuit presented in this paper is feasible. The THD of the inverter output voltage could be reduced to a certain extent by this method.展开更多
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
文摘Total harmonic distortion (THD) is one of the key technical indexes of inverter output voltage. Optimization o f switching points and filter parameters could ensure the switching-point-preset sinusoidal pulse width modulation (SPWM) inverters with low harmonyic content in theory.The THD value would be increased by switching time delay of power devices and control circuit. A new control coecuit with delay time compensation is presented in this paper. With this control scheme, the output of the inverter could be basically identified with the theory given.Test results of experimental circuit verify that the control circuit presented in this paper is feasible. The THD of the inverter output voltage could be reduced to a certain extent by this method.
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.
