Method and apparatus for controlling an electric motor

摘要

The present invention provides a method for controlling the output power of a permanent magnet electric motor ( 102 ) using a control means ( 106 ). The control means ( 106 ) includes a means ( 134 ) for measuring motor speed ( 134 ) and motor phase current ( 134 ), and a means for controlling motor phase current ( 110 ) to a desired level. A known relationship between motor phase current and motor torque is then employed by a torque controller so that motor shaft torque can be controlled. A power limiting means ( 128 ) then limits the output mechanical power of the motor by dividing a limit value of power by the motor speed to produce a maximum allowable torque setting for that speed.