Dual Volts-per-Hertz Control of Double-Inverter-Fed Wound Rotor Induction Machine

Abstract

Double-inverter-fed wound rotor induction machine (DI-WRIM) is a two-port machine capable of maintaining rated torque even at twice the rated speed. Such machines are gaining popularity in high-speed and high-power applications for their versatility and degrees of freedom in control. The existing control methods for DI-WRIM are all based on the dynamic model of the machine and the associated controller structures are complex with multiple controllers. This article proposes a novel control scheme for DI-WRIM based on the steady-state model which requires only one controller. The proposed control scheme has the capability to operate the machine in both sub and super-synchronous modes in all the four quadrants in torque-speed plane. The simplicity of the proposed dual volts-per-hertz control method can be compared to the very popular scalar control used in cage-rotor induction machine drives. Mathematical derivation of the control law with appropriate approximations is discussed. Experimental results are presented from a 5-hp, 8-pole wound rotor induction machine drive.