Kaj so the glavni prevodni spojke preklop moč napajalnik?
1 Pogosti način in diferencial način šum pot model
V the switching power supply, it is formirano due do the sklopka kapacitivnost CW med the primarna in sekundarna navitja od the visoke frekvence transformator, the the stray capacitance CK med the power tube and the radiator, the parazitski parametri of the power cev sam, in the mutual coupling med the printed wires. parazitski parametri takšni as vzajemni induktivni, samoinduktivnost, vzajemna kapacitivnost, samokapacitivnost, in impedanca oblika običajni način hrup in diferencial-način hrup poti, tobratno oblikovanje skupni način in diferencialni način vodeni interferenčni. Osnovano na analiza of parazitski parameter modeli of upornost, induktivnost, in kapacitivnost vklopljenje naprave, transformator, in natisnjeno žice, the hrup trenutno pot model of pretvornik lahko be dobljeno.
2 Visoka frekvenca model glavni komponenti od the vezje
The notranja parazitska induktivnost in kapacitivnost od moč stikalo cev afekt visoka frekvenca zmogljivost tokokroga Te kapacitivnosti vzrok visoka frekvenca interferenca puščanje tok tok do kovina substrat, in tam is a potepuška kapacitivnost CK med the moč cev in radiator za varnost razlogi. , the toplota umivalnik is običajno povezani v zemeljski, ki zagotavlja a pot za skupni način hrup.
When the PWM converter is working, along with the operation of the switching device, common mode noise is also generated accordingly. As shown in Figure 1, for a half-bridge converter, the drain voltage of switch Q1 is always U1, and the source potential changes between 0 and U1/2 with the change of the switching state; the source potential of Q2 is always 0 , the drain potential changes between 0 and U1/2. In order to maintain good contact between the switch tube and the radiator, an insulating gasket or insulating silica gel with good thermal conductivity is often added between the bottom of the switch tube and the radiator. This makes it equivalent to a parallel coupling capacitor CK between point A and ground. When the status of switching tubes Q1 and Q2 changes, causing the potential of point A to change, a noise current Ick will be generated on CK, as shown in Figure 2. This current reaches the chassis from the radiator, and there is a coupling impedance between the chassis, the ground, and the main power line, forming a common-mode noise path as shown by the dotted line in Figure 2. As a result, the common-mode noise current generates a voltage drop on the coupling impedance Z between the ground and the main power line, forming common-mode noise.
