Sung-Jin Jang, Hyung-Woo Lee, and Kyo-Beum Lee, "A Control Method to Extend the Lifetime of Floating Capacitor in Dual Inverter with Floating Capacitor," in Proc. ICEE Conf., 2022. > Paper

This paper presents a control method to improving floating capacitor lifetime for the dual inverter with a floating capacitor. 

The dual inverter with floating capacitor is composed of double two-level inverters and bulk electrolytic capacitor. Because of disconnecting one 

inverter from the input power source, the voltage of floating capacitor can be boosting through open end winding interior permanent magnetic 

synchronous motor (OEW-IPMSM). The one inverter with floating capacitor outputs additional reactive voltage for the OEW-IPMSM through the 

floating capacitor. The floating capacitor is one of the components with vulnerable reliability in the dual inverter. A current ripples of floating capacitor cause to temperature rise and wear-out failure of the dual inverter. The accumulated thermo-mechanical damages from the temperature rise reduce 

the capacitor lifetime and reliability of the dual inverter system. There is a control method to increase the voltage of the floating capacitor to reduce 

the root mean square (RMS) value of the ripple current. The dual inverter has a large switching loss because it has twelve switching devices and high 

voltage of floating capacitor. Because the switching losses increases, the control method using high voltage is inappropriate to reduce RMS value of 

the ripple current. When the presented control method is used, the ripple current of the floating capacitor is controlled depending on the capacitor 

lifetime. The presented method controls the current ripple factor and set output reactive power of inverter 2. The effectiveness of the presented 

control method is verified through simulation results.