Method and apparatus for commutation of drive coils in a linear drive system with independent movers

A motor controller for controlling commutation of drive coils to control operation of a mover along a track in a linear drive system, the motor controller comprising:

• at least one first input operative to receive a position feedback signal corresponding to a position of the mover along the track;
• at least one second input operative to receive a reference signal corresponding to a desired operation of the mover along the track;
• a power segment operative to provide a current to each of a plurality of drive coils operatively connected to the power segment;
• and
• a processor operative to:
• identify a portion of the plurality of drive coils proximate the position of the mover along the track, wherein an electromagnetic field generated by the current flowing in each coil is operative to engage at least one drive magnet on the mover,
• determine a desired force applied to the mover as a function of the reference signal, of the position of the mover, and of a control mode selected for the motor controller,
• generate a current reference signal for each coil in the portion of the plurality of drive coils proximate the position of the mover along the track according to one of a plurality of commutation modes, wherein the commutation mode determines the current reference for each of the plurality of drive coils as a function of the desired force applied to the mover, and
• transmit the current reference signal for each drive coil in the portion of the plurality of drive coils proximate the position of the mover to the power segment, wherein the power segment provides the current to each coil according to the corresponding current reference signal.

A method for controlling commutation of drive coils to control operation of a mover along a track in a linear drive system, the method comprising the steps of:

• obtaining a position of the mover along the track with a motor controller;
• identifying a plurality of drive coils proximate the position of the mover with the motor controller, wherein an electromagnetic field generated by a current flowing in each of the plurality of drive coils is operative to engage at least one drive magnet on the mover;
• receiving a reference signal at the motor controller corresponding to a desired operation of the mover;
• determining a desired force to be applied to the mover as a function of the reference signal, of the position of the mover, and of a control mode selected for the motor controller;
• selecting one of a plurality of commutation modes in the motor controller to determine a current reference for each of the plurality of drive coils;
• and
• determining the current reference for each of the plurality of drive coils with the motor controller as a function of:
• the selected commutation mode, the position of the mover, the desired force to be applied to the mover, and a back-emf value for each of the plurality of drive coils.