Ultra High Speed operation of BLDC motor with enhanced motor dynamics for space limited applications

This paper proposes new method of operating BLDC motor which extends operating speed beyond the limit set by conventional 120° conduction mode of operation, without field weakening and having same inverter dc bus voltage. Concepts of Phase Extension mode and Ultra High Speed mode are introduced. Also in the paper it is shown that the proposed `phase extension´ mode of operation can produce additional average torque, above the conventionally available torque. Thus increasing torque-to-weight ratio of BLDC motor drive system makes it desirable for space constrained applications like Aerospace. Proposed modes of operation will enhance the motor dynamics in the wide speed range. Analysis, simulation results and pictorial descriptions are presented.