Ripple (electrical)

When a DC voltage from a sinusoidal alternating voltage is produced by rectifying, thus always produces a pulsating voltage from the DC and overlaid AC. Simple circuits to reduce the AC component using a smoothing capacitor or a smoothing reactor, often both together. The fact that despite smoothing still a ( then mostly unwanted ) AC component remains is denoted by ripple.

Also, regulated power supplies and switching power supplies have one, albeit much smaller ripple.

The following definitions apply equally to electric voltage and amperage. For simplicity, this text is limited to the voltage.

A mixed variable u (t ) is composed of a DC component and an AC component

For a quantitative description of the AC component is the authoritative standard DIN 40110-1 this ( " AC quantities "; March 1994) three size ratios to:

• Vibration level as the ratio of the rms value of the alternating component U ~ to the RMS value of the total mixed size U

• Ripple as the ratio of RMS value of the AC component to the DC value amount U_

• Schwankungswelligkeit ( ripple factor ) as the ratio of oscillation width or peak - to-peak ( before peak -to-peak value USS) to sum ​​the DC value

The vibration level can take values ​​0 ( for DC ) ... 1 ( AC ) or 0 ... 100 %. The ripple and the Schwankungswelligkeit are in the range 0 ( DC) ... ∞ ( AC). Occasionally ∙ 20 dB specified instead ru ru also lg.

Not listed in this standard, the ripple is ω. It is defined as

This is the form factor F is the ratio of RMS to rectified value

Which in the present context ( voltage without change of sign ) rectified value is the same as the amount of the direct value. With true after elementary conversion match the definition of the ripple with the above definition of the ripple.

The indicator for the ripple in some cases only the alternating component is specified as an rms value U ~ or peak -to-peak value USS. Such information is given in millivolts or volts.