Vector controlled AC motor drives for long cable application: Analysis of harmonics at motor terminal

摘要

The implementation of long cable connection to AC drives creates harmonic in motor current and voltage, which in turn affects the power quality of the system. This paper presents a detailed analysis of harmonics at motor terminal of vector controlled AC drives for long cable applications. The long cable is represented by 50-m and 100-m cable. Experimental tests are conducted under no-load and load operating conditions with respect to various switching frequency and speed. The real-time implementation of AC drives is done using MATLAB/Simulink program and dSPACE DS1103 controller board. From the analysis, the cable length does not affect the speed response due to high-frequency switching operation of PWM signal. However, it increases the harmonic content in current and voltage of the motor. The THD current and THD voltage increase 5.5% and 12.5% in average respectively when long cable is applied. It is found that the THD voltage is greatly affected by long cable compared to the THD current. These findings provide important insight for future research which is mitigation method of voltage harmonics for the AC drives with long cable connection.