Gilsu Choi

• Doctor of Philosophy
• Engineer at General Motors Company

This work presents the results of an investigation focused on the rotor eddy-current losses of a permanent magnet (PM) synchronous machine that is equipped with fractional-slot concentrated windings (FSCW). Major spatial harmonics that induce the most significant rotor eddy-current losses are identified and evaluated. Time-stepped finite element (F...

This paper investigates the impact of machine topology and parameters on the fault-mode characteristics of permanent magnet synchronous machines (PMSMs) exposed to asymmetrical short-circuit (ASC) faults, one of the most dangerous faults in terms of peak current amplitudes and demagnetization risks. Simulations using an equivalent circuit model com...

This paper investigates the three-phase symmetrical short-circuit (SSC) characteristics of a permanent magnet synchronous machine (PMSM). Closed-form solutions are derived to predict both the steady-state and transient response of a PMSM to three-phase SSC faults. The developed expressions account for the impact of prefault operating conditions and...

A design approach is presented to mitigate demagnetization vulnerability in permanent magnet synchronous machines (PMSMs) by proper selection and design of stator windings and rotor configurations. First, a comparative analysis of the stator demagnetizing MMFs and leakage inductances for surface PM machines equipped with integral-slot distributed w...

This paper presents the results of experimental tests designed to verify analytical predictions of the rotor demagnetization characteristics of a 0.6 kW (cont.) 9-slot/6-pole fractional-slot concentrated winding (FSCW) interior PM (IPM) synchronous machine. The demagnetization characteristics of the rotor magnets in this commercially-produced FSCW-...

A design approach is presented to mitigate demagnetization vulnerability in surface permanent magnet synchronous machines (SPMSMs) by proper selection and design of stator windings and rotor configurations. First, a comparative analysis of the stator demagnetizing MMFs and leakage inductances for surface PM machines equipped with integral-slot dist...

This work investigates maximum efficiency control strategies of permanent magnet (PM) traction machine drives that are adopted in General Motors (GM) hybrid and electric vehicles. First, three different current vector control techniques, Maximum Torque Per Ampere (MTPA), Maximum Torque Per Motor Loss (MTPML), and Maximum Torque Per System Loss (MTP...

This paper presents the results of experimental tests designed to verify analytical predictions of the rotor demagnetization characteristics of a 0.6 kW (cont.) 9-slot/6-pole fractional-slot concentrated winding (FSCW) interior PM (IPM) synchronous machine. The demagnetization characteristics of the rotor magnets in this commercially-produced FSCW-...

This paper presents the calculated demagnetization characteristics of different types of permanent magnet synchronous machines (PMSMs) under the influence of demagnetizing MMF contributed by the stator currents (i.e., armature reaction). The demagnetization of NdFeB magnets is quantified in terms of demagnetized magnet volume and loss of magnet rem...

This paper investigates the impact of machine topology and parameters on the fault-mode characteristics of permanent magnet synchronous machines (PMSMs) exposed to asymmetrical short-circuit (ASC) faults, one of the most dangerous faults in terms of peak current amplitudes and demagnetization risks. Simulations using an equivalent circuit model com...

This paper investigates the three-phase symmetrical short-circuit characteristics of a permanent magnet synchronous machine (PMSM). Closed-form solutions are derived to predict both the steady-state and transient response of a PMSM to three-phase symmetrical short-circuit (SSC) faults. The developed expressions account for the impact of pre-fault o...

This paper presents the dynamic response of an interior permanent magnet synchronous machine (IPMSM) drive to various fault conditions and their effects on the PM demagnetization characteristics. Attention is focused on modeling the IPMSM drive including nonlinear magnetic behavior under asymmetrical inverter fault conditions, demonstrating the sig...

This paper presents a specialized design evaluation tool for electric machines intended for use in electric vehicles that seeks to maximize the machine's efficiency in the operating regions that most closely correspond to the vehicle's driving schedules. The influences of different designs on a production battery-electric vehicle are studied. A com...

This paper presents a new graduate-level course that is designed, developed, and taught at the University of Wisconsin-Madison to further advance the education for wind power technologies. The objective of this course is to provide an in-depth coverage of control of electric drives for wind turbines with an emphasis using state-of-the-art modeling...

Paper # 2011-01-0344; DOI 10.4271/2011-01-0344

Autorickshaws are one of the chief modes of transport in many Asian countries. In India, these vehicles are mainly used as taxis. Since there is heavy congestion on the roads of India, the small size and narrow body of this three wheeled vehicle is perfectly suited to navigate the roads. These vehicles are usually powered by a two or four stroke ga...