High-Performance Interior Permanent Magnet Synchronous Motor for Electric Vehicles over Wide Speed Range

Abstract

Battery electric vehicle (EVs) has become very popular with the interest of environmentally friendly electric vehicles rather than the conventional-Internal Combustion Engine (ICE) vehicles. To run with power, it needs the continuous wide working speed range of motors for the stable power region, strong power in high speed and a great start rallying torque in the low speed. This paper presents a simulation model of an Interior Permanent Magnet Synchronous Motor IPMSM for electric vehicle (EV) traction purpose in MATLAB/Simulink. This consists of Field Oriented Control (FOC), and runs Flux Weakening (FW) controller. 25 The EV market grows rapidly, hence the IPMSM is the best motor for such application due to that the motor has high torque-to -current ratio, high power mathematical eqns. We were able to identify behavior of the motor using FOC control also below base speed, when using FW control at rated speeds; the model indicated response was robust [1]. In addition, we will demonstrate greater high-speed torque using a feedforward flux weakening controller method, with constant power. The responses of speed, below and above rated speed will be stated regarding the results of the simulation. This model approach can suggest a rough level of advice on how to select an appropriate IPMSM configuration regarding distinct vehicle applications and drive conditions.

Introduction

The global push toward sustainable transportation is accelerating due to climate change concerns, urban air pollution, and the declining availability of fossil fuels. Electric Vehicles (EVs), especially those using Interior Permanent Magnet Synchronous Motors (IPMSMs), are seen as a key solution due to their energy efficiency, environmental benefits, and superior dynamic performance.

?? Importance of IPMSMs in EVs

• IPMSMs are widely adopted in EVs for their:

  • High torque-to-current ratio

  • Broad speed range

  • Thermal and structural durability

• They combine magnetic and reluctance torque, making them suitable for both urban and highway driving conditions.

???? Control Systems for IPMSM

• The research focuses on implementing advanced control strategies to optimize IPMSM performance:

  • Field-Oriented Control (FOC): Manages torque and flux independently, crucial for accurate low-speed control.

  • Flux Weakening (FW): Allows operation beyond the motor’s base speed by injecting negative d-axis current, reducing back-EMF and avoiding voltage saturation.

???? Simulation and Evaluation

• A simulation of the control system is tested using the FTP-75 driving cycle, mimicking real-world urban driving patterns.

• The results verify that the system improves performance and maintains control across various conditions.

???? Mathematical Modeling of IPMSM

• The d–q axis transformation (Clarke & Park) simplifies the analysis and control by converting 3-phase stator quantities into two orthogonal components.

• Key equations govern:

  • Stator voltages as functions of current, flux, and speed.

  • Electromagnetic torque (including both magnetic and reluctance components).

  • Mechanical dynamics of the rotor.

Key equations:

• Vd=Rsid+dλddt−ωeλqV_d = R_s i_d + \frac{d\lambda_d}{dt} - \omega_e \lambda_qVd?=Rs?id?+dtdλd??−ωe?λq?

• Vq=Rsiq+dλqdt+ωeλdV_q = R_s i_q + \frac{d\lambda_q}{dt} + \omega_e \lambda_dVq?=Rs?iq?+dtdλq??+ωe?λd?

• Te=32p[λmiq+(Ld−Lq)idiq]T_e = \frac{3}{2}p [\lambda_m i_q + (L_d - L_q) i_d i_q]Te?=23?p[λm?iq?+(Ld?−Lq?)id?iq?]

• Jdωmdt=Te−TL−BωmJ \frac{d\omega_m}{dt} = T_e - T_L - B\omega_mJdtdωm??=Te?−TL?−Bωm?

? Flux Weakening (FW) Strategy

• Necessary at high speeds where back-EMF may exceed inverter voltage.

• Injects negative IdI_dId? to reduce rotor flux and keep operation within safe voltage/current limits.

• Ensures continuous performance in the constant power region of the motor.

Voltage and current constraints:

• Id2+Iq2≤Imax\sqrt{I_d^2 + I_q^2} \leq I_{max}Id2?+Iq2??≤Imax?

• Vd2+Vq2≤Vmax\sqrt{V_d^2 + V_q^2} \leq V_{max}Vd2?+Vq2??≤Vmax?

???? Integration with Vehicle Control System

• Control architecture includes:

  • Speed monitoring to transition between FOC and FW modes.

  • Dynamic adjustment of IdI_dId? and IqI_qIq? to balance performance and stay within hardware limits.

• Simulations show smooth transitions and enhanced efficiency at all speeds.

???? Implementation of Control Scheme

• A cascade control strategy is used:

  • FOC for low-speed, torque-focused control.

  • FW for high-speed, voltage-regulated control.

• PI controllers manage current and speed loops.

• Clarke and Park transformations allow switching between rotating and stationary reference frames, enabling accurate control of inverter inputs.

Conclusion

The efficiency of combining feedforward Flux Weakening (FW) and Field-Oriented Control (FOC) techniques over a broad operating speed range was shown by the simulation study and control implementation of the IPMSM-based electric vehicle propulsion system. The model, developed and executed in MATLAB/Simulink, was subjected to the standardized FTP-75 urban driving cycle, which closely mirrors real-world stop-and-go traffic conditions. The results affirm that the proposed control scheme ensures precise torque regulation at low speeds and extends motor capability beyond base speed without compromising system stability or energy efficiency. The vehicle exhibited responsive speed tracking, consistent torque output, and smooth transitions during acceleration and deceleration phases. The inverter voltage and three-phase current waveforms remained within safe and operational limits, demonstrating robust electrical performance. Battery behaviour, in terms of current, voltage, and SOC, confirmed efficient energy usage and successful implementation of regenerative braking during deceleration periods. The validity of the system was also demonstrated by realistic handling of the load torque fluctuations, which are demanded by the driving profile. Together, these results demonstrate the practicability and appropriateness of applying the novel IPMSM and advanced control strategies for EVs. The approach developed in this research work, beyond enhancing the drivability and the energy efficiency of the vehicle, offers to the EV system a rate of scalability capable to meet the efficiency and the performance requirements of the modern electric mobility solutions.

References

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Copyright

Copyright © 2025 Pravalika Malaparaju, Dr. N. V. Ramana. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.