DC-Bus Capacitor Discharge Control Strategy for PMSM Drives System: Electric Vehicles

Abstract

Electric vehicles have become increasingly popular for their high efficiency and zero emissions, making them vital for sustainable transportation. The Permanent Magnet Synchronous Motors (PMSM) are widely used in Electric Vehicles, because of the Active discharge mechanism play a critical role in maintaining the safety and reliability of Electric Vehicle (EV) system. The proposed control strategy ensures that, the DC bus capacitor voltage is safely discharged to an acceptable level during emergency fault conditions. This paper proposed a robust winding-based capacitor discharge strategy that effectively utilizes the inherent machine windings of the PMSM as an alternative discharge path when the active circuit is unavailable. The control strategy discharge mechanism operates in two distinct stages to ensure rapid and controlled voltage reduction. In the first stage, a large flux-enfeebling in d-axis current which is injected to quickly suppress the back electromotive force (EMF), thereby achieving an immediate reduction in the DC bus voltage. In the second stage, a voltage regulation process compensates for residual energy caused by switching losses and inductive effects, maintaining the voltage at a safe level until the system stabilizes. This approach eliminates the dependence on external resistors for improving the system safety and cost-effectiveness. During normal operation to enhance the dynamic performance of the electric vehicle system, a PMSM drive systems with an integrated ANFIS controller is used for speed regulation.

               The proposed control strategy synergizes the adaptive learning capability of neural networks with the rule-based reasoning of fuzzy logic, to resulting in improved nonlinear control characteristics compared with PI, FUZZY and ANN Controllers. This paper presents the design and simulation of an PMSM drive system with ANFIS based speed control for EV system. To validate the effectiveness of the proposed system, the MATLAB Simulink model is implemented on a three-phase Surface-mounted PMSM (SPMSM) drive platform. The PMSM drive with ANFIS-controller, exhibits precise and stable speed control, even under rapid transients and varying load conditions and enhanced performance during standard operation offering a reliable, intelligent and cost-efficient solution for modern electric vehicle drive systems.