DC-Link Capacitor Dimensioning with Lifetime Calculation Considerations for PMSM Drives: A Practical Framework for Enhanced Performance

A crucial component of the functioning of a three-phase inverter in Permanent Magnet Synchronous Motor (PMSM) drives is the DC-link capacitors. The functioning of the inverter may be affected by an excessive voltage ripple caused by a DC connection capacitor of insufficient size. In contrast, an oversized capacitor can increase the system cost and volume and affect the transient response. Moreover, electrolytic capacitors, commonly used in DC-links, face significant lifetime limitations due to thermal stress from ripple current and voltage fluctuations. This paper presents a comprehensive methodology for selecting and sizing DC-link capacitors in inverter-fed PMSM drives, focusing on minimizing voltage ripple while ensuring compliance with the lifetime requirement for the electrolytic capacitors. Using a closed-loop simulation model, the functionality of the new method with the upgraded DC-link capacitor is confirmed based on system parameters, load profiles, and operational conditions.