Speaker
Description
Growing environmental concerns have increased the demand for high-power-density electric propulsion systems. One way to achieve higher power density is through the use of superconducting technology. In particular, no-insulation (NI) high-temperature superconducting (HTS) coils offer improved power density due to their ability to carry high currents and withstand external disturbances.
Superconductors are commonly used in the field coils of electric propulsion systems to reduce AC losses. However, using superconducting field coils in rotating parts creates several challenges. First, delivering high current requires slip rings and brushes, which makes the system more complex. Second, designing a cooling system for rotating parts is difficult. These challenges make the rotor design more complicated and limit the speed of operation.
Homopolar topology can be an alternative to these problems by keeping the field coil stationary, removing the need for slip rings, brushes, and complex cooling systems. Therefore, the homopolar topology is better suited for applications that require relatively high speeds.
This study investigates the basic design of a homopolar motor using NI HTS coils to improve power density in electric propulsion systems. It identifies key design parameters and compares the power density of different designs. Additionally, since NI HTS coils have no insulation between turns, current can flow in the radial direction, and radial current may be induced by changes in the external magnetic field during motor operation. Therefore, this study analyzes the parameters (inductance, contact resistance Rc, and time constant) of the NI HTS field coil according to key design parameters, and analyzes how the NI HTS field coil behavior (leak current and heat generation) occurring during operation affects the motor's operation characteristics (average torque, torque density, and torque ripple).
