Supercapacitor City Minibus Bonded NdFeB IPMSM Propulsion System: Design and System Modeling Methodology via a Case Study and Laboratory Experiments

This article presents the structure, analytical description, simulation results, and rather extended laboratory scale experiments on a minibus electric drive, using a supercapacitor (SC) as a storage element. The traction is implemented by a single interior permanent magnet synchronous motor (IPMSM), with Bonded-NdFeB Spoke PMs in axis d and flux barriers in axis q, fed by an inverter with vector control strategy. The power interface between the SC, the drive, and the power line (for SC fast charging) is implemented by a hybrid bidirectional DC/DC converter (HBDC). The case study refers to a 7t minibus on an urban driving cycle profile simulation, confirming the initial theoretical considerations and proposed technical solutions. In terms of lab work a 1:20 torque scale (20Nm) 5 kW at 2.4-4.8 krpm IPMSM was designed, manufactured and tested both under no load and load conditions with simulation and test results under steady state compared and measured transients that confirm the expected performance.