Design, Commissioning and Testing of an Electrodynamometer Based on PM Synchronous Machines

Abstract

This paper addresses the design, simulation, commissioning and testing of an electrodynamometer (ED) to assessthe dynamic performance of Electric Vehicles (EV). The EV-ED system is comprised of two electric machines coupledmechanically. The traction machine is a 7.75 kW Permanent Magnet Synchronous Motor which is controlled by meansof a vector control and it is coupled mechanically to a similar machine which is used as a mechanical load. The loadmachine was fed by two DC/AC converters connected by the DC bus allowing bidirectional power flow. Theelectrodynamometer was controlled by means of a National Instruments electronic board and Labview software.Several load profiles and inertias were programmed to emulate an Electric Vehicle (EV). The traction machine drivewas implemented with a PP75T120 Powerex Inverter. PWM generation and control strategy were implemented on aMC56F8357 Freescale Digital Signal Controller (DSC). The speed control of the traction machine was validated fordifferent driving cycles. Matlab/Simulink simulations of the machine control and electrodynamometer along withexperimental results illustrating the response of the machine control under the characteristic load profile of an EV arepresented and analyzed. Traction and regenerative breaking stages are analyzed and discussed broadly.