Optimum On-Line DC-Link Voltage Regulation for Efficiency Impromovement of Motor Drives.

The purpose of this paper is to propose an efficiency improvement method for motor drives with DC-link voltage optimization control. A four-switch buck-boost DC/DC converter is used for DC-link voltage regulation in front of the inverter to provide regulated voltage. The advantages of bidirectional buck-boost converter include providing wider voltage regulation range and energy recovery capability. The proposed method is developed based upon the minimization of Total Harmonic Distortion of motor current and tuning the DC-link voltage on-line adaptively. Neither motor parameter nor look-up table is required.Experimental results for permanent-magnet synchronous motor drives are presented to validate the effectiveness of the proposed method. The overall efficiency improvement of motor drives with buck-boost converter can go up to 23.55% under low speed as compared with that without DC-link voltage regulation and buck-boost converter for the proposed DC-link voltage optimization method.