Sign in Subscribe
Electronic components

Advances in Capacitance Estimation for Electric Vehicle Inverters

Strategic Insights

— 1 min read

Researchers at Kookmin University have made a significant breakthrough in estimating the capacitance of DC link capacitors in electric vehicle inverters. The study aims to improve the reliability and stability of these inverters by developing a new method for predicting the capacitor lifespan. The proposed method analyzes the voltage and current characteristics of the capacitor during space vector pulse width modulation (SVPWM)-based control of a real-time motor, eliminating the need for additional signal injection or circuits.

Key Takeaways:

  • The study highlights the importance of predicting the lifespan of DC link capacitors in electric vehicle inverters to ensure reliability and stability.
  • A new method for estimating capacitance is proposed, which analyzes voltage and current characteristics during SVPWM-based control without additional signal injection or circuits.
  • A capacitor current analysis equation is established to improve capacitance estimation performance, considering voltage sampling time and inverter dead time (DT).
  • The proposed method is confirmed to be reliable by comparing it with manual measurement under various motor driving and constraint conditions.
  • The research includes a comparison of the proposed method with manual measurement under various motor driving and constraint conditions.
  • The study mentions that the remaining lifespan of the DC link capacitor can be predicted if the initial capacitance can be estimated in real-time.
  • The research suggests that a failure can be diagnosed and prevented by predicting the remaining lifespan of the capacitor.
  • The study's findings are based on real-time motor control, and the proposed method does not affect the motor control.

Statistics:

  • The proposed method requires an additional circuit for implementation, with the limitation that real-time motor control is affected by additional signal injection.
  • The new method estimates capacitance online and offline without additional signal injection.
  • The capacitance estimation performance is improved by considering voltage sampling time and inverter dead time (DT).
  • The proposed method is reliable under various motor driving and constraint conditions, with a mean absolute percentage error (MAPE) of less than 5%.
  • The study mentions that the remaining lifespan of the capacitor can be predicted if the capacitance decrease amount can be estimated.

Sources:

  • "Online Capacitance Estimation for the DC Link Capacitor of PWM Inverter." IEEE Access, 2025,13():170735-170747. (https://doi-org.sdpl.idm.oclc.org/10.1109/ACCESS.2025.3615584)
  • "Studies from Kookmin University in the Area of Engineering Published (Online Capacitance Estimation for the DC Link Capacitor of PWM Inverter)." Journal of Engineering. October 20, 2025; p 3965.

Read more