Assessment of the Feasibility of Using a Synchronous Homopolar Motor Instead of an Induction Motor in a Traction Drive With a Wide Constant Power Speed Range

Abstract

Synchronous homopolar machines (SHMs) have established their merit in various applications, including pulse heating generators and automotive generators. They offer such advantages as a simple and dependable rotor design devoid of windings and permanent magnets, and a reliable field winding consisting of a small number of concentrated coils on the stator. This makes SHMs promising as traction motors for off-highway vehicles, such as mining dump trucks. Mining dump trucks confront the challenges of transporting hefty loads on dirt roads at speeds up to 60 km/h and conquering steep inclines. Although conventional induction motors (IMs) are widely used in these trucks, they suffer from rotor overheating, vulnerability to broken rotor bar faults, and substantial low-frequency current oscillations when braking on a slope. These problems stimulate the search for alternatives. This article conducts a theoretical analysis comparing optimized designs of IM and SHM for driving a mining dump truck with a payload of 90 tons. The comparison encompasses critical parameters such as efficiency, losses, torque ripple, required inverter power, dimensions, weight, active material cost, and inverter reliability. The study employs the downhill simplex method for optimization and the finite element method. The study shows that the benefits of SHM include reduced active material costs and improved motor and inverter reliability.

Keywords

• Constant power speed operation range
• haul truck
• synchronous machines with DC excitation
• synchronous homopolar motor
• Nelder-Mead optimization algorithm
• optimum design