Enhanced Thermal Management in Oil Spray-Cooled Motors: A Novel Approach to Replacing NTC Sensors

Abstract

<div>Motor temperature plays a critical role in controlling pump speed and regulating coolant flow to prevent overheating during motor operation. Presently, negative temperature coefficient (NTC) sensors are commonly used for motor temperature measurement, typically installed at the motor winding’s end for ease of installation. However, in oil spray-cooled motors, the temperature distribution is uneven due to the spray pipe, leading to lower temperatures near the pipe compared to other areas. This results in a challenge where relying solely on NTC measurements at the winding end may not meet the motor’s cooling requirements. To address this issue and improve temperature signal accuracy, a novel approach has been developed that utilizes four signals derived from the motor controller: motor speed, motor torque, along with oil pump speed, oil temperature. Employing the lumped parameter method, a model established in Simulink aims to estimate the average temperature in the motor’s high-temperature region. Subsequently, this value is corrected and directly utilized as an input signal for motor thermal management. The proposed approach not only enhances motor temperature monitoring accuracy but also mitigates operational risks, thereby prolonging motor lifespan and enhancing its overall safety.</div>