In the circuit, a large capacity electrolytic UNL2003ADR capacitance Cl is connected in parallel with a small capacitance C2. Cl is a large capacity filter capacitor of lOOOyF, C2 is a small capacitor of only O. OlyF, which is a high frequency filter capacitor for filtering high frequency components.This large and small capacitance parallel circuit is very common in the power supply circuit.
circuit analysis/High frequency filter circuit editing
Atlas
Atlas[1] (1)The power circuit rectifies and filters 220V AC market power. Because there are a lot of high-frequency interference in the power grid, it is necessary to filter the high-frequency interference components in the power circuit. The high frequency filter capacitor circuit in the power supply circuit is the circuit which plays the role of high frequency filtering. (2) in theory, in the same wayA capacitor with large capacity at one frequency has a small capacitance reactance, so that a capacitor C2 with small capacity after one or two capacitors are connected in parallel does not work. However, due to the inductance characteristics of large capacitors (described earlier in the introduction of electrolytic capacitance characteristics), its impedance at high frequencies is higher than that at low frequencies.(3) in order to compensate for the shortage of Tun Rong Cl at high frequency, a small capacitance C2 is connected in parallel. Because of the small capacity of the small capacitor, it can overcome the inductance characteristics in manufacturing, so the small capacitor C2 almost does not have inductance. When the operating frequency of the circuit is high, the capacitance reactance of the small capacitance C2 is very small, so high.The frequency interference signal is filtered to ground by a small capacitance C2. (4) In this circuit, most of the unidirectional pulsating DC voltages of the rectifier circuit are low frequency AC components, and the small capacitors of these AC components do not work (because the small capacitors have large capacitance reactance to the low frequency AC components and are equivalent to the open circuit).At this time, the main reason is that the large capacitance Cl is working, and the Cl flow is the low frequency AC component. (5) For the high frequency component, the frequency is relatively high, the large capacitor Cl is in the open circuit state and does not work, and the small capacitor C2 is in the working state because its capacitance reactance is far less than the impedance of C1, which is used to filter out various high frequency interference signals.Number, so the high-frequency component that flows through C2 is.
fault analysis/High frequency filter circuit editing
(1)The circuit fault analysis of filter capacitor Cl is the same as the fault analysis of the former filter capacitor circuit. (2) When the high-frequency filter capacitor C2 is open, the normal operation of the whole circuit is almost unaffected. Occasionally, high-frequency interference faults occur and high-frequency screaming occurs. When the C2 breaks down, the filter circuit has no DC.Working voltage output, and will fuse the power supply circuit fuse; when C2 leakage, filter circuit output DC working voltage will be reduced.