Linear Parameter Varying Control for Permanent Magnet Synchronous Motor-Based Electrified Powertrain

Traction Electric Machines (EM) are the most integral part of the electrified powertrain of Electric Vehicles (EV). Among all traction electric machines, based on high efficiency over a large speed range, high-power density, reliability, high torque to inertia ratio, control maturity and high fidelity Permanent Magnet Synchronous Motor (PMSM) in EV is the preferred choice for today's automotive industry. In this paper, a state-of-the-art control strategy based on Linear Parameter Varying (LPV) control is designed for an electrified powertrain to address the crucial challenge of torque derating. A PMSM-based EV is modeled by taking into account the variations in operating and ambient temperature. The derating torque results in reduced efficiency and hence power loss, unable to meet road loads, and reduced life span of the electrified powertrain. A closed-loop torque compensation control architecture with LPV-based Field Oriented Control (FOC) has been designed to manage the thermal effects. The testing has been performed for EM operation against the Federal Urban Driving Schedule (FUDS) while considering thermal effects using a high-fidelity powertrain simulator. The performance comparison with the conventional PI-based FOC strategy shows that at 65°C LPV controller maintains the root mean square error (RMSE) in torque profile to 0.024[Nm] but in the conventional PI-based FOC strategy, the RMSE is 11.058 [Nm]. It is verified experimentally on a PMSM drive controlled by Labview and an ARM Cortex-based microcontroller. Results show that LPV control is more effective and efficient in catering to winding resistance variations due to the elevated temperature.