Reliability Improvement of Voltage Regulator Modules by a Virtual Series Voltage Source

Abstract

Output voltage deviation is a key performance index of voltage regulator modules (VRMs) with consecutive load transients. Usually, a large-capacity filter capacitor bank is used in VRMs to reduce the voltage deviation and stabilize the output voltage during transients. However, capacitors are one of the most vulnerable links in power electronic converters. For reliability reasons, it is essential to reduce the capacitance requirement while guaranteeing the transient performances of VRMs. Focusing on this, many efforts have been made to optimize the design of VRMs, where the transient auxiliary circuit-based scheme is a popular one. Unfortunately, there exists a large number of additional components in the existing auxiliary circuits. Considering this issue, in this article, we present a virtual series voltage source (VSVS) based auxiliary circuit scheme, which has minimum component counts. By using a controlled coupled inductor as the VSVS, the proposed scheme enables VRMs to have a relatively small transient voltage overshoot and without needing large bulk capacitance. Moreover, considering different control schemes with the same designing aim, the number and the electrothermal stress of critical components (e.g., capacitors) of VRMs are different; it is difficult to compare directly their advantages and disadvantages. Regarding this issue, this article investigates the converter-level reliability of VRMs with different control schemes. Taking a 12–3.3 V VRM as a case study, the reliability benchmarking results illustrate that the proposed scheme can significantly improve the reliability of VRMs.