Control system and method for a rotating electromagnetic machine

A system for controlling a rotating electromagnetic machine including a stator having a plurality of phase windings, a rotor that rotates relative to the stator, and a drive connected to the phase windings for energizing the windings, the control system comprising:

• an estimator connectable so the machine for receiving signals representing the phase winding voltage and rotor position;
• the estimator outputting parameter estimations for an electrical model of the machine based on the received voltage and rotor position;
• a torque model receiving the parameter estimations from the estimator, the torque model outputting estimates of torque for associated rotor position-phase current combinations;
• and
• a controller having input terminals for receiving a torque demand signal and the rotor position signal, the controller adapted to output a control signal to the drive in response to the torque demand and rotor position signals and the torque model.

A rotating electromagnetic machine system, comprising:

• a stator;
• a plurality of phase windings situated in the stator,
• a rotor situated so as to rotate relative to the stator,
• a rotor position sensor outputting a signal representing the rotor position relative to the stator,
• a drive connected to the phase windings for energizing the windings;
• an estimator connected to the phase windings and the rotor position sensor to receive signals representing the phase winding voltage and rotor position, the estimator outputting parameter estimations for an electrical model of the machine based on the received voltage and rotor position;
• a torque model receiving the parameter estimations from the estimator, the torque model outputting estimates of torque for associated rotor position-phase current combinations;
• and
• a controller having input terminals for receiving a torque demand signal and the rotor position signal, the controller adapted to output a control signal to the drive in response to the torque demand and rotor position signals and the torque model.

A method of determining a non-load dependent cogging torque in a permanent magnet motor having a stator, a plurality of stator windings having terminals connectable to a source of power for energizing the windings, a rotor situated to rotate relative to the stator, the method comprising:

• spinning the rotor unloaded at a predetermined angular velocity;
• measuring voltage and current at the motor terminals;
• determining the rotor positions associated with the voltage and currant measurements;
• developing a first mathematical model based on the measured voltage and rotor position to describe electrical behavior of the machine;
• developing a second mathematical model via a mathematical transform of the first mathematical model to describe torque characteristics of the machine;
• energizing the windings such that the rotor holds a predetermined position;
• and
• calculating the cogging torque for the predetermined position via the second mathematical model.

A system for controlling a rotating electromagnetic machine including a stator having a plurality of phase windings, a rotor that rotates relative to the stator, and a drive connected to the phase windings for energizing the windings the control system comprising:

• an estimator connectable to the machine for receiving signals representing the phase winding voltage and rotor position;
• the estimator outputting parameter estimations for an electrical model of the machine based on the received voltage and rotor position at predetermined times, the predetermined times including times when the rotating machine is not operational;
• a torque model receiving the parameter estimations from the estimator, the torque model outputting estimates of torque the associated rotor position-phase current combinations;
• and
• a controller having input terminals for receiving a torque demand signal and the rotor position signal, the controller adapted to output a control signal to the drive in response to the torque demand and rotor position signals and the torque model.