Analiza elektromagnetska kompatibilnost dizajn metoda of prebacivanje napajanje napajanje
1 Internal izvori od smetnji
● Prebacivanje krug
L prebacivanje krug je uglavnom komponirano of a prebacivanje cijev i a visokofrekventno transformator. The switching tube and its toplina sudoper have distribuirana capacitance with the olovo žice inside the case and power supply, and the du/dt it generrates has a large amplitude pulse with wide propusnost and rich in harmonic. Switching tube load for high-frequency transformer primary coil, is an inductive load. When the original conduction of the switching tube off, the leakage inductance of the the high-frequency transformer generrates a counterpotential E=-Ldi/dt, the value of which is proportional to the rate of change of the the collector struja, proportional to the leakage inductance, iterated on the shutdown voltage, the formation of the shutdown voltage spike, thus forming a conduction interference.
● ispravljač dioda of ispravljač krug
The output ispravljač diode cuts off with a reverse current whose recovery time to zero is related to factors such as junction capacitance. It produces a large current variation di/dt under the influence of transformer leakage inductance and other distribution parameters, generating strong high-frequency interference with frekvencije up to tens of megaherca.
● Spurious parametri
As a result of operating at higher frequencies, the characteristics of the low-frequency components in the switching power supply change, resulting in noise. At high frequencies, the spurious parameters have a great influence on the characteristics of the coupling channel, and the distribution capacitance becomes the channel for electromagnetic interference.
2 Vanjski izvori od smetnji
Vanjski izvori smetnje može biti podijeljeno u napajanje opskrba interferencije i munje interferencije, i napajanje opskrba interferencije to "common mode" i "diferencijal mode" način. At the iste vrijeme, due to the AC power grid directly connected to the rectifier most and filter circuit, in half a cycle, only the peak time of the input voltage input current, resulting in in a a very low input power factor of the power supply (about 0.6). Moreover, this current contains a large number of current harmonic components, which can "pollute" the grid with harmonics.
