Optimal Modulation Method for Reducing Ripple Current and Power Loss of DC-link Capacitor in Multi-drive Systems

Abstract

This paper proposes a modulation method that can significantly reduce the ripple current and power loss of the DC-link capacitor of multi-drive systems. It is based on a derived analytical model for capacitor ripple current with an arbitrary number of drives connected in parallel at the DClink side. Both the low-frequency and high-frequency current components are minimized by the optimal phase shift of modulation and carrier signals. Benchmark studies of multidrive systems with 2 to 20 drives reveal that the total capacitor Root Mean Square (RMS) current is reduced to 34.3%~15.9%. Proof-of-concept experimental results from multi-drives with identical and different individual loading conditions verify the theoretical analysis and effectiveness of the proposed method.