Self-Sensing via Flux Injection With Rapid Servo Dynamics Including a Smooth Transition to Back-EMF Tracking Self-Sensing

Abstract

Self-sensing control at zero and low speed has been widely implemented and studied by many researchers. This technique is based on injecting a high-frequency voltage or current into the motor to estimate the motor position and speed from the measured motor quantities like current or voltage. Tracking the motor back-EMF or flux signal has been used to control motors during medium- and high-speed operations. This article proposes a high-frequency flux injection (HFFI) based self-sensing using deadbeat-direct torque and flux control to control permanent magnet servo motor at zero and low speed with ideally zero torque ripple, unlike the standard current or voltage injection techniques. The HFFI is combined with a back EMF self-sensing technique to control the motor during medium- and high-speed operations. This article also proposes a method for a smooth transition between these two methods. The proposed controller is used to control different types of slightly salient servo motors during dynamic servo operations.