Power Supply Smoothing (Ripple/C)
Residual ripple ΔU, required C, load current and frequency
Calculation
Quick Introduction
After rectification, residual ripple remains. It depends on load current, capacitance, and ripple frequency. Higher load current or lower capacitance increases ΔU.
This tool is directly aligned with existing rectifier calculator pages and supports fast pre-sizing of smoothing capacitors.
Sizing schema (simplified):
1) Define load current and allowed ripple
2) Select rectifier type (half/full wave)
3) Compute C and choose next higher standard value
Formulas (MathJax)
\[\Delta U \approx \frac{I_{load}}{C\,f_{ripple}}\]
\[C = \frac{I_{load}}{\Delta U\,f_{ripple}}\]
\[I_{load}=\Delta U\,C\,f_{ripple}\]
\[f_{ripple}=f\;(half\ wave),\quad f_{ripple}=2f\;(full\ wave)\]
Symbol Legend
- \(\Delta U\): residual ripple [Vpp]
- \(I_{load}\): load current [A]
- \(C\): smoothing capacitance [F]
- \(f\): mains frequency [Hz]
- \(f_{ripple}\): recharge pulse frequency [Hz]
Examples
Example 1 (full-wave): \(I=1.5\,A\), \(C=4700\,\mu F\), \(f=50\,Hz\) ⇒ \(f_{ripple}=100\,Hz\), \(\Delta U\approx3.19\,Vpp\).
Example 2: target \(\Delta U=2\,Vpp\), \(I=1.5\,A\), full-wave \(100\,Hz\) ⇒ \(C\approx7500\,\mu F\).
Detailed Description & Summary
The ripple estimate for capacitor-input rectifier supplies is a practical first-order model. For higher precision, include ESR, transformer resistance, diode drops, and dynamic load behavior.
At higher currents or stricter ripple targets, significantly larger capacitance may be required, or a different power-supply topology may be more suitable.
Summary
- Computes ΔU, C, or I depending on design intent
- Handles half-wave and full-wave ripple frequency
- Directly usable for rectifier power supply pre-sizing
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