Design of Mass Moment of Inertia Measurement Equipment and Application to an Electric Power Motor

Information on mass moment of inertia is crucial for constructing a dynamic model for complex systems. Methods that accurately provide this information using low-cost and simple procedures can accelerate the process of building a dynamic model. To address these issues, this study introduces a novel device that utilizes a spiral spring to measure the mass moment of inertia. The device consists of a base structure, a vertical column axis with a thrust bearing, a test bed, and a spiral spring. With a given initial angular displacement, the test object on the bed undergoes free rotational vibration. Measuring the period of this vibration provides an estimated value for the mass moment of inertia of the test object. A validation process for the accuracy of the measurement device using objects with known mass properties demonstrated that the device can estimate the mass property with less than one percent error within a designed mass range. Subsequently, the newly developed measurement device was employed to measure the mass moment of inertia of a power motor in an electric car. Accuracy was further assessed by comparing the results with reference values obtained from different experiments.