Multi-Physics Design of a Modular BLDC Motor-Drive System for Automotive Cooling Fans

The main contributions of this paper can be itemized as follows: • Proposing an application-oriented industry-level solution for automotive thermal management electromechanical sub-system. • Comprehensive system-level design, modeling and validation. • Considering a multi-physics approach for design and evaluation including electromagnetic, thermal and mechanical sectors. • Industry-based fully-modular prototype development and testing with the mass-production capability. This article outlines an application-oriented system-level multi-physics design process for a 13.5-volt, 33.5-ampere external-rotor brushless direct current (BLDC) motor, specifically developed for automotive cooling fan applications, while adhering to all automotive design and manufacturing standards. The motor's dynamic transient behavior is analyzed using finite element method (FEM) simulations. The modular design of the system allows for the integration of a sensorless drive with the BLDC motor. The sensorless drive system determines the rotor position by detecting phase voltage zero-crossings using a virtual neutral point approach. Given the stringent automotive requirements, thermal evaluation of the drive module is crucial. Therefore, the thermal performance of the drive module is simulated using 3D FEM-based thermal simulations. To verify the simulation results, an industrial prototype motor, built in accordance with automotive industry standards, is manufactured. Experimental tests, including operational and thermal evaluations, are conducted to assess the system accuracy. The findings indicate that the power consumption of the motor is less than 450W, the produced torque is more than 1.2Nm, and the temperature rise of the motor and drive is less than 25°C, which ensures the proper functioning of the fan components under the hood. Therefore, the proposed cooling-system design and manufacturing approach can be a viable and practical framework for the development of automotive electromechanical sub-systems.