Abstract: A motor apparatus includes a multi-lane permanent magnet synchronous motor having at least two sets of phase windings, and a control circuit. The control circuit selectively connects a first direct current power source to the motor phase windings of a first set of the motor phasing windings to form a first lane. The control circuit may also selectively connect a second direct current power source to the motor phase windings of a second set of the motor phasing windings to form a second lane. The control circuit may cause current to flow in the motor that meets a current demand from a current demand circuit. During at least one mode of operation, the control circuit may apply waveforms to a motor phase winding which causes an actively controlled transfer of energy from the first direct current source of the first lane into a component of the second lane.

Abstract: An electromagnetic motor comprising an inner stator comprising a plurality of stator teeth, each surrounded by one or more turns of electrical wire, a controller which generates a set of currents that are applied to phase windings of the inner stator to generate a pattern of magnetic poles spaced around the inner stator, the spacing between the magnetic poles being larger than the spacing between adjacent teeth of the inner stator, an outer stator that is concentric with the inner stator and comprises an alternating set of magnet poles, the spacing between adjacent magnet poles being smaller than the spacing of the magnetic poles of a first array created by the controller, and an intermediate rotor part that is located between the inner stator and the outer stator and comprises an array of pole pieces, in which the pole pieces of the intermediate rotor part shape a magnetic flux acting between the inner and outer stators, and whereby in use the controller is arranged to control a torque applied to the rotor p

Abstract: A method of determining an electrical angle offset of a motor position sensor mounted to a multi-phase electric motor, the method comprising rotating a rotor of the multi-phase electric motor at a motor velocity using an external drive system, measuring a motor phase voltage of each phase of the multi-phase electric motor, the motor phase voltage comprising a back-EMF generated by the rotation of the motor, converting the motor phase voltage to a DQ reference frame to form a DQ motor phase voltage and calculating the electrical angle offset from the DQ motor phase voltages.

Abstract: A control system for an electric motor comprises a controller which receives as an input a demanded motor current and produces at an output an intermediate voltage demand signal, a voltage demand signal correction means arranged to generate a voltage demand correction signal, and a combining means arranged to combine the intermediate voltage demand signal and the voltage demand correction signal to produce an actual voltage demand signal that is applied to the motor by pulse width modulation of the switches of a motor bridge driver. The correction signal compensates for unwanted non-linearities caused by interlock delays in the switching of the motor bridge switches.

Abstract: A motor apparatus comprises a permanent magnet synchronous motor circuit having a plurality of lanes, each lane comprising a plurality of unbalanced phases. A current demand circuit which receives a torque demand signal having a value equal to the torque that is to be generated by the motor apparatus and generates a respective current demand signal for each lane indicative of the current to be applied to each phase of the lane to achieve the demanded torque. A first drive circuit and a second drive circuit each comprise a plurality of switches which selectively connect the phases of a respective one of the plurality of lanes to a supply such that PWM modulated currents flow in each of the phases that correspond to the demanded current. The current demand circuit is adapted to modify one or both of the current demand signals such that one or both lanes additionally generate a set of radial forces that are applied to the rotor of the motor that do not net to zero.

Abstract: A method of determining an electrical angle offset of a motor position sensor mounted to a multi-phase electric motor, the method comprising rotating a rotor of the multi-phase electric motor at a motor velocity using an external drive system, measuring a motor phase voltage of each phase of the multi-phase electric motor, the motor phase voltage comprising a back-EMF generated by the rotation of the motor, converting the motor phase voltage to a DQ reference frame to form a DQ motor phase voltage and calculating the electrical angle offset from the DQ motor phase voltages.

Abstract: A linear actuator comprising a first fixed portion comprising a linear array of stator teeth, each surrounded by one or more turns of electrical wire, a controller which generates a set of currents that are applied to phase windings of the first fixed portion to generate a pattern of magnetic poles along the array of stator teeth, a spacing between the magnetic poles being larger than a spacing between adjacent stator teeth of the first fixed portion, a second fixed portion that comprises an alternating set of magnet poles, a spacing between adjacent poles being smaller than the spacing of the magnetic poles of the first fixed portion created by the controller, and a movable output portion that comprises a linear array of pole pieces that extend along a length of the moveable output portion that is greater than a stroke length of the actuator and longer than a length of the fixed portion, whereby in use a length of the movable output portion is at all times located between the first and second fixed portions,

Abstract: A motor apparatus includes a multi-lane permanent magnet synchronous motor having at least two sets of phase windings, and a control circuit. The control circuit selectively connects a first direct current power source to the motor phase windings of a first set of the motor phasing windings to form a first lane. The control circuit may also selectively connect a second direct current power source to the motor phase windings of a second set of the motor phasing windings to form a second lane. The control circuit may cause current to flow in the motor that meets a current demand from a current demand circuit. During at least one mode of operation, the control circuit may apply waveforms to a motor phase winding which causes an actively controlled transfer of energy from the first direct current source of the first lane into a component of the second lane.

Abstract: A method of controlling a motor of an electric power assisted steering system, the motor having a plurality of phases, the method comprising taking as an input an input signal indicative of a desired assistance torque and determining from the desired assistance torque a voltage to be applied to each of the phases of the motor, in which the step of determining the voltage to be applied to each of the phases comprises limiting the voltage determined to be applied to each of the phases of the motor dependent upon the voltage provided by a power supply to the motor.

Abstract: A control system for an electric motor comprises a controller which receives as an input a demanded motor current and produces at an output an intermediate voltage demand signal, a voltage demand signal correction means arranged to generate a voltage demand correction signal, and a combining means arranged to combine the intermediate voltage demand signal and the voltage demand correction signal to produce an actual voltage demand signal that is applied to the motor by pulse width modulation of the switches of a motor bridge driver. The correction signal compensates for unwanted non-linearities caused by interlock delays in the switching of the motor bridge switches.

Abstract: A motor apparatus comprises a permanent magnet synchronous motor circuit having a plurality of lanes, each lane comprising a plurality of unbalanced phases. A current demand circuit which receives a torque demand signal having a value equal to the torque that is to be generated by the motor apparatus and generates a respective current demand signal for each lane indicative of the current to be applied to each phase of the lane to achieve the demanded torque. A first drive circuit and a second drive circuit each comprise a plurality of switches which selectively connect the phases of a respective one of the plurality of lanes to a supply such that PWM modulated currents flow in each of the phases that correspond to the demanded current. The current demand circuit is adapted to modify one or both of the current demand signals such that one or both lanes additionally generate a set of radial forces that are applied to the rotor of the motor that do not net to zero.

Abstract: A linear actuator comprising a first fixed portion comprising a linear array of stator teeth, each surrounded by one or more turns of electrical wire, a controller which generates a set of currents that are applied to phase windings of the first fixed portion to generate a pattern of magnetic poles along the array of stator teeth, a spacing between the magnetic poles being larger than a spacing between adjacent stator teeth of the first fixed portion, a second fixed portion that comprises an alternating set of magnet poles, a spacing between adjacent poles being smaller than the spacing of the magnetic poles of the first fixed portion created by the controller, and a movable output portion that comprises a linear array of pole pieces that extend along a length of the moveable output portion that is greater than a stroke length of the actuator and longer than a length of the fixed portion, whereby in use a length of the movable output portion is at all times located between the first and second fixed portions,

Abstract: An electromagnetic motor comprising an inner stator comprising a plurality of stator teeth, each surrounded by one or more turns of electrical wire, a controller which generates a set of currents that are applied to phase windings of the inner stator to generate a pattern of magnetic poles spaced around the inner stator, the spacing between the magnetic poles being larger than the spacing between adjacent teeth of the inner stator, an outer stator that is concentric with the inner stator and comprises an alternating set of magnet poles, the spacing between adjacent magnet poles being smaller than the spacing of the magnetic poles of a first array created by the controller, and an intermediate rotor part that is located between the inner stator and the outer stator and comprises an array of pole pieces, in which the pole pieces of the intermediate rotor part shape a magnetic flux acting between the inner and outer stators, and whereby in use the controller is arranged to control a torque applied to the rotor p

Abstract: A rotary encoder assembly comprises an annular track comprising an alternating pattern of at least two different encoding regions; a first detector and a second detector each arranged to produce a respective alternating output signal as the track of encoding regions rotates about its axis past the detector, the combined values of the two output signals assuming a plurality of unique states with the states changing from one to another as the encoder rotates. A memory stores compensation values, each value being associated with a respective one of the possible state changes that can occur when the combined values of the two output signals change upon movement of the encoder track, and each indicative of an average error in the position at which the corresponding change of state occurs.

Abstract: A control system for an electric motor comprises a current sensing means arranged to produce a current sensing output indicative of electric current in the motor, current control means arranged to receive the current sensing output and to output a voltage demand indicative of voltages to be applied to the motor, and current sensing correction means arranged to monitor the voltage demand to measure distortion in the current sensing output and to generate a correction signal which is arranged to correct the distortion.

Abstract: A rotary encoder assembly comprises an annular track comprising an alternating pattern of at least two different encoding regions; a first detector and a second detector each arranged to produce a respective alternating output signal as the track of encoding regions rotates about its axis past the detector, the combined values of the two output signals assuming a plurality of unique states with the states changing from one to another as the encoder rotates. A memory stores compensation values, each value being associated with a respective one of the possible state changes that can occur when the combined values of the two output signals change upon movement of the encoder track, and each indicative of an average error in the position at which the corresponding change of state occurs.

Abstract: A method of controlling a motor of an electric power assisted steering system, the motor having a plurality of phases, the method comprising taking as an input an input signal indicative of a desired assistance torque and determining from the desired assistance torque a voltage to be applied to each of the phases of the motor, in which the step of determining the voltage to be applied to each of the phases comprises limiting the voltage determined to be applied to each of the phases of the motor dependent upon the voltage provided by a power supply to the motor.

Abstract: A control system for an electric motor comprises a current sensing means arranged to produce a current sensing output indicative of electric current in the motor, current control means arranged to receive the current sensing output and to output a voltage demand indicative of voltages to be applied to the motor, and voltage demand correction means arranged to generate a correction signal and to use the correction signal and the voltage demand to produce a corrected voltage demand.

Abstract: A drive system, for a multi-phase brushless electric motor comprising a plurality of phases, comprises: a drive circuit including switch means arranged to vary the phase voltage applied to each of the phases so as to switch the motor between a plurality of active states; and control means. The control means is arranged to control the switch means so as to provide PWM control of the phase voltages to control the mechanical output of the motor. The control means is arranged to define a sequence for all of the active states and, for each PWM period, to allocate state times for the states required for that period to generate a desired net voltage, and to order the required states in the same order as they occur in the sequence.

Abstract: A control system is provided for an AC electric motor which comprises a rotor and a stator and a plurality of phase windings connected in a star formation, each winding having one end connected to a common neutral point and another end arranged to have a terminal voltage applied to it. The control system comprises switching means arranged to control the terminal voltages applied to the windings and control means arranged to control the switching means so as to switch it between a plurality of states in each of a sequence of PWM periods. The control means is further arranged to measure the voltage at the neutral point at sample times within the PWM periods and to generate from the measured voltages an estimation of the rotational position of the rotor.