A System-Level Design for Reliability of Integrated Motor Drives

Because of increasing the importance of using an integrated motor drive (IMD) in industry, considering reliability in the design of IMD plays a crucial role. An IMD consists of an electrical motor (EM) and an electrical drive (ED) in a single unit. This configuration helps to eliminate cables and reduce volume which yields increased power density. The most important factors in the failure of EM and ED as a single unit are thermal effects and vibration. In the case of an IMD, a high-reliability design is of paramount importance because there are mutual thermal impacts between the EM and ED. Both EM and ED have components that are susceptible to failure, leading to system failure. Components such as shaft, bearing, stator, and rotor may fail in the EM, and components such as power modules, DC link capacitors, and microcontroller unit (MCU) may degrade due to the stress and thermal in the ED. This paper proposes a method to assess the reliability of an IMD systematically. The proposed algorithm includes three main stages, which are IMD specifications, design for reliability, and system-level functionality testing. The mutual impact between the EM and ED is considered in the design for the reliability stage which is subdivided into three: analysis, initial design, and verification. Applying this algorithm to design an IMD results in reliable operation under various conditions.