Frequency-hybrid vector control for sensorless induction motor and its application to electric vehicle drive

As one of most useful sensorless vector control schemes for an induction motor drive, the frequency-hybrid (FH) vector control scheme has been proposed by one of the authors, which has the following high performance attributes: (1) it can make machines to produce more than 200% rated torque at standstill; (2) in both motoring and regenerating modes, rated torque can be produced even in very slow speed range including zero-speed and zero-frequency; (3) it accepts inertia larger than 200 times of rotor; (4) it has high tracking ability to variable speed command; (5) it can accept zero-speed command and settles the machines at a stable standstill with no vibration; and (6) it accepts instant injection of rated load even for zero-speed control. Most of the above performance is required for realization of a sensorless electric vehicle (EV). This paper presents design, realization and field test results of a radical new sensorless EV based on the EH vector control scheme, and clarifies its usefulness