Analysis and performance of direct flux control scheme for dynamic torque control in AC drives

Control of current during torque and flux vector dynamics has been a major concern in a dynamic torque control scheme. Voltage limitation, saturation of current controllers, current control in overmodulation and six-step range and parameter sensitivity are some of these concerns. Hence, it is desirable to have a fast torque dynamic without explicit control of current. The Direct Flux Control (DFC) scheme achieves dynamic torque control with the fastest torque dynamic that Is physically possible, without an explicit current control. Does such a scheme provide an Inherent current control? In this paper, we present transient analysis of the inherent current control feature shown by Direct Flux Control. Theoretical analysis along with experimental results prove that no explicit current control is mandatory to achieve dynamic torque control.