ripple current

When ripple current ( engl. ripple current), of ripple in the German standards " superimposed AC ", sometimes referred to in technical publications and pulsating direct current is called in electrical alternating current of any frequency and waveform, which is superimposed on a direct current. It occurs mainly after the rectifying an AC voltage at the next filter capacitor. The special shape of the ripple current with the rectified mains frequency 100 Hz ( full-wave rectification) was formerly called " ripple current ".

Effects

One of the DC voltage ripple voltage caused in a capacitor charging and discharging. These cause an rms current which generates a power loss on the equivalent series resistance (ESR ) of the capacitor, which is converted into heat. The capacitor heats up. For ceramic and plastic foil capacitors and tantalum electrolytic capacitors with this warming has little negative impact on the working life of the capacitors when defined temperature limits are not exceeded. For aluminum electrolytic capacitors with liquid electrolytes, however, the ripple current generated by the internal heat in a shortening of the expected life of the capacitors result. Ripple currents that are outside the specified limits of the affected capacitors can cause damage to the components.

Another side effect is the emission of electromagnetic alternating fields which adversely affect the EMC behavior of a circuit. Ripple currents also arise typically fast gear changes, for example in digital technology or by so-called "cross Conducting " in switching power supplies and H bonds, but also during the commutation of DC machines. If they can not be ripple currents prevent one tries to eliminate through blocking capacitors directly at the source the majority of the AC component.