Constant power speed range extension of surface mounted PM motors

摘要

A circuit and method for controlling a rotating machine (11) in the constant horsepower range above base speed uses an inverter (15) having SCR's (T1-T6) connected in series with the primary commutation switches (Q1-Q6) to control turn off of the primary commutation switches and to protect the primary commutation switches from faults. The primary commutation switches (Q1-Q6) are controlled by a controller (14), to fire in advance or after a time when the back emf equals the applied voltage, and then to turn off after a precise dwell time, such that suitable power is developed at speeds up to at least six times base speed.