Abstract: A method for determining an initial position of a rotor of a polyphase motor is described. The method comprises determining current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor; identifying a set of modelled current change values according to a modelled behaviour of the motor, in which the modelled current change values represents modelled positions of the rotor under the modelled behaviour; and comparing the current change values to the set of modelled current change values to identify the initial rotor position from the modelled positions. A system implementing the method is also described.

Abstract: A method for attenuating switching noise from back electromotive force (EMF) observations in a motor is described. The motor is controlled by pulse width modulation (PWM) signals provided at a PWM frequency. The method comprises sampling back EMF observed in the motor at a sampling frequency at least two times greater than the PWM frequency to obtain over-sampled back EMF readings. The oversampled readings may be used in a raw or filtered form to commutate the motor. A system implementing the method is also described.

Abstract: A method for adjusting a rotational speed of a rotor in a polyphase motor from a first speed towards a second, faster speed when the motor is commutating according to a commutation scheme at a first commutation phase angle is described. The method comprises selecting an advanced phase angle relative to the first commutation phase angle for commutating the motor; and adjusting the commutation scheme to be commutating at the advanced phase angle, so that the rotational speed of the rotor increases from the first speed towards the second speed as the motor is commutating at the advanced phase angle. A system implementing the method is also described.

Abstract: Methods for evaluating back electromotive force (EMF) in a polyphase motor is described. The methods include monitoring back EMF in the motor after a commutation of the motor, and evaluating the back EMF only after a back EMF event occurs after the commutation of the motor. The methods may also include monitoring a total current appearing on all phase windings of the motor after a rotor of the motor begins to rotate, and evaluating back EMF only after the total current is within a predetermined margin of the current supplied to the motor. Systems implementing the methods are also described.

Abstract: A method for attenuating switching noise from back electromotive force (EMF) observations in a motor is described. The motor is controlled by pulse width modulation (PWM) signals provided at a PWM frequency. The method comprises sampling back EMF observed in the motor at a sampling frequency at least two times greater than the PWM frequency to obtain over-sampled back EMF readings; and filtering the over-sampled back EMF readings to remove switching noise and obtain cleaned back EMF observations. A system implementing the method is also described.

Abstract: A system and method for sensor less control of a stepper motor is described. The system and method includes estimation of the position of a rotor of the motor by way of sensing circuitry on the windings of the motor, without the use of positional sensors. The system and method of stepper motor control further includes magnetic field optimization for increasing the torque generating component of a magnetic field generated by stators of the motor, and magnetic field weakening for countering some of the effects of back electromotive force generated by the magnetic rotor.

Abstract: The modular conveyor system comprises N interconnected track sections, forming a continuous track, wherein each track section features a plurality of individually controlled coils stretching along the length thereof. Plural pallets, each having thrust producing magnets, travel independently alone the track. The track also comprises multiple linear encoder readers spaced at fixed positions therealong, and each pallet includes a linear encoder strip having a length R greater than the spacing E between the readers. Track section controllers associate the encoder strips with only one reader at any time in order to resolve the position of the pallets based on the fixed position of the readers and the relative positions of the strips in relation thereto. The section controllers also regulate and commutate the coils of the corresponding track sections in order to independently control each pallet. Communication links interface adjacent section controllers situated in adjacent track sections.

Abstract: The modular conveyor system comprises N interconnected track sections, forming a continuous track, wherein each track section features a plurality of individually controlled coils stretching along the length thereof. Plural pallets, each having thrust producing magnets, travel independently alone the track. The track also comprises multiple linear encoder readers spaced at fixed positions therealong, and each pallet includes a linear encoder strip having a length R greater than the spacing E between the readers. Track section controllers associate the encoder strips with only one reader at any time in order to resolve the position of the pallets based on the fixed position of the readers and the relative positions of the strips in relation thereto. The section controllers also regulate and commutate the coils of the corresponding track sections in order to independently control each pallet. Communication links interface adjacent section controllers situated in adjacent track sections.