Patent ID: 8493017
Filing Date: 2013-07-23
Classification: H02P

Abstract:
1. An electrical drive, comprising: a motor having a rotor and a stationary stator; a coil arrangement provided on said stator; a motor controller for controlling the motor, said motor controller being configured for passing current through said coil arrangement for generating an excitation field; a plurality of coil winding sections arranged on said coil arrangement, each coil winding section having at least a first coil section and a second coil section, said first coil section having a first polarity, and said second coil section having a second polarity; and at least one polarity reversing switch for switching said plurality of coil sections of a coil winding section between a first state, in which all coil sections in said coil winding section have the same polarity, and a second state in which at least one of said coil sections of said plurality of coil sections has a polarity opposite a polarity of the remaining coil sections in said coil winding section; wherein said motor controller is configured to operate said motor with a first rotation speed/torque characteristic having a first gradient and with a second rotation speed/torque characteristic having a second gradient being different from said first gradient, wherein at least one coil winding section further comprises a first coil section and at least one second coil section, said first coil section having a first number of turns, and said second coil section having a second number of turns, wherein said first and second coil sections are magnetically coupled for producing a magnetic sum field when said first and second coil sections have the same polarity, and for producing a magnetic difference field when said first and second coil sections have an opposite polarity, and wherein said difference field is weaker than said sum field as well as associated induced voltages, substantially by a factor which is equal to a sum of the first and second numbers of turns divided the difference between the first and second numbers of turns (i=n