Reliability Analysis of Capacitors in Voltage Regulator Modules With Consecutive Load Transients
Zhaoyang Zhao, Dao Zhou, Pooya Davari, Junlong Fang, Frede Blaabjerg
Abstract
Capacitors are critical in voltage regulator modules (VRMs), which contribute to store energy and stabilize the output voltage during load transients. Usually, VRMs work with consecutive load transients, which would bring more electrothermal stress to capacitors and affect the reliability of capacitors compared with the steady-state operation. Recently, some efforts have been made to investigate the reliability of capacitors in power electronic converters. Unfortunately, transient processes are commonly ignored, which can impair the accuracy of the lifetime estimation. Regarding this issue, this letter investigates the influence of transients on the damage of capacitors in VRMs. A 150-W VRM is introduced as a case study. First, the electrothermal stresses during steady state and transients are analyzed. Then, the lifetime calculation is considered from a single capacitor to hybrid capacitor banks. In addition, a suitable capacitor configuration of capacitor banks is also provided in order to maximize its lifetime.