Accurate heat loss evaluation of water-cooled electric motors using a differential ultrasonic calorimeter

Measuring thermal losses of electric motors are important for their design optimization and correct pricing after manufacture. This measurement can be conducted by measuring the temperature difference of the motor coolant (commonly water) between the coolant's inlet and outlet. High speed of measurement facilitates testing various load scenarios and manufacture throughput; high measurement accuracy and resolution enables correct conclusions on efficiency of various design alterations and price bracketing of manufactured pieces. Ultrasonic temperature sensors can fast sense temperature with high resolution and accuracy across the complete ultrasonic pathway. Conventional high resolution ultrasonic sensors are expensive; however, oscillating ultrasonic temperature sensors can be implemented using mass produced transducers and electronic parts which cost a fraction of the price of conventional high resolution ultrasonic measurement equipment. The presented ongoing research focuses on development of a differential ultrasonic oscillating temperature sensor for evaluation of power losses in electrical motors. Computer simulations, electronic and firmware design, and experimental results are presented and discussed.