Vector control method and driving characteristics of parallel-connected induction motor drives fed by a Matrix Converter

A Matrix Converter is an electricity converter to operate direct convertion of Variable Voltage Variable Frequency (VVVF) without Direct Convertion (DC) link part. Some applied examples of motor drives by the Matrix Converter (Fig.1). This paper presents basic characteristic of parallel-connected dual induction motor drives with the Matrix Converter. Purposes of this system are low cost and saving space in the industrial field to operate plural motors. However, in case of the unbalanced loads, both motors are unstable and each motor makes the speed response differenced to cause the rotor flux change. We indicate the new strategy to control stably by applying the average value control in slip-frequency vector control. Moreover, we propose to decrease the speed response of two motors by choosing feed-forward term in the speed control system applying two degrees of freedom control (2DOF).