Reduced Position Error and Overshoot Control Using Modified Integrator-Based QPR Controller and SMO for Limp Home Mode PMSM-Driven EV

The conventional sliding-mode observer used for position estimation in permanent magnet synchronous machine (PMSM) drives for electric vehicle (EV) applications experiences chattering caused by the sign function and phase delay when employing a low-pass filter (LPF). Additionally, the conventional integrator used in the proportional-integral (PI) controller suffers from DC drift and initial value problems during practical implementation, resulting in a significant overshoot and speed errors in the speed tracking profile. This study presents a modified integrator (MI) for digital implementation that eliminates the initial value problem and reduces the DC drift issue. This paper also proposes a MI-based quasi-proportional resonant (MIQPR) controller for the position sensorless control of PMSM-driven EVs using SMO. This approach eliminates the need for a sign function and LPF, thereby reducing the phase delay and effectively minimizing the position error. The proposed control scheme is experimentally validated through closed-loop control utilizing space-vector-modulation-based direct torque and flux control (SVM-DTFC). This ensures a fast dynamic response and reduces overshooting and undershooting of the speed response. The proposed method was validated through experiments conducted on a 2.2 kW PMSM and WAVECT WCU300 field-programmable gate array (FPGA) controller.