Lifetime Estimation for Aluminum Electrolytic Capacitors in Active Power Filter

Reliability issues brought by the lifetime of Aluminum electrolytic capacitors (Al E-Caps) in the DC bank of power electronics equipment has captured attention recently. In the active power filter (APF), the Al E-Caps in the DC bank suffers harmonics on a broader spectrum, and this makes the reliability issues in this application more critical. In this paper, the harmonic currents are quantitatively derived with the consideration of the coupling effect among each harmonic. Due to the frequency-character of the Al E-Caps' ESR, the inside thermal-electrical stress of the Al E-Caps in APF is analyzed in the frequency domain following by the lifetime estimation for four different application scenarios. The theoretical analysis is verified by a 100 A APF.