Abstract: An electric power assisted steering system comprises a motor adapted to apply an assistance torque to a portion of a steering shaft in response to a motor drive signal from a drive circuit, in which the motor comprises a synchronous wound field motor of the kind comprising a stator and a rotor, in which the rotor includes at least one pole and at least one coil winding associated with the pole and the stator comprises a number of phase windings, and in which the drive circuit which is configured to provide current in the coils of the stator and rotor during operation of the motor.

Abstract: An electric power assisted steering system comprises a motor adapted to apply an assistance torque to a portion of a steering shaft in response to a motor drive signal from a drive circuit, in which the motor comprises a synchronous wound field motor of the kind comprising a stator and a rotor, in which the rotor includes at least one pole and at least one coil winding associated with the pole and the stator comprises a number of phase windings, and in which the drive circuit which is configured to provide current in the coils of the stator and rotor during operation of the motor.

Abstract: A stator for a multi-phase electric motor comprises a plurality of teeth for each phase. The windings on two teeth from one phase are formed from a single length of conductor. The windings on a first one of the teeth being formed at least in part from two sections of the conductor spaced apart along the length of the conductor, and the windings on a second one of the teeth being formed from an intermediate section of the conductor between the spaced apart sections.

Abstract: A drive system for a motor having a rotor and a phase winding (a, b, c) comprises; a drive circuit including switch means associated with the winding a, b, c for varying the current passing through the winding; rotor position sensing means arranged to sense the position of the rotor; control means arranged to provide drive signals to control the switch means; a power input for connection to a power supply at a nominal voltage; and boost means in electric communication with the power input and power output, and controllable to boost the nominal voltage to a higher voltage for application to the winding.

Abstract: A power steering system comprises a hydraulic circuit, a pump arranged to pressurize hydraulic fluid and valve means arranged to control the flow of pressurized fluid in the hydraulic circuit to control the steering force provided by the system. The system further comprises a motor arranged to drive the pump and control means arranged to control operation of the motor, and the control means is arranged to determine the position of the motor from a plurality of parameters by means of a position determining algorithm.

Abstract: A rotor structure for a motor comprising a rotor having an end surface; a shaft extending from the end surface; an encoder member attached to the end surface of the rotor; and a coupler coupled to the shaft adjacent to the encoder member for coupling a further member to the shaft, in which the coupler surrounds the shaft and has a lip associated therewith, the lip extending from the coupler towards the encoder member so as to define a void between the coupler and the encoder member. The void defined by the rotor structure may act to contain matters such as swarf that is ejected from the rotor when the encoder member is fixed to the rotor. The rotor may be used in a motor of an electric power assisted steering (EPAS) system.

Abstract: A stator for a multi-phase electric motor comprises a plurality of teeth for each phase. The windings on two teeth from one phase are formed from a single length of conductor. The windings on a first one of the teeth being formed at least in part from two sections of the conductor spaced apart along the length of the conductor, and the windings on a second one of the teeth being formed from an intermediate section of the conductor between the spaced apart sections.

Abstract: A rotor structure for a motor comprising a rotor having an end surface; a shaft extending from the end surface; an encoder member attached to the end surface of the rotor; and a coupler coupled to the shaft adjacent to the encoder member for coupling a further member to the shaft, in which the coupler surrounds the shaft and has a lip associated therewith, the lip extending from the coupler towards the encoder member so as to define a void between the coupler and the encoder member. The void defined by the rotor structure may act to contain matters such as swarf that is ejected from the rotor when the encoder member is fixed to the rotor. The rotor may be used in a motor of an electric power assisted steering (EPAS) system.

Abstract: A drive system for a three phase brushless AC motor is arranged to optimize the transistor switching pattern to improve power output whilst allowing current measurement in all of the phases using a single sensor. This is achieved by defining voltage demand vectors x where more than two states are required to meet a minimum state time requirement determined by the single sensor method, and calculating three or more state vectors which produce the demanded vector x whilst still allowing single current sensing. Various methods of optimising the PWM pattern so as to give maximum output whilst using single current sensing are also disclosed.

Abstract: A drive system for a motor having a rotor and a phase winding (a, b, c) comprises; a drive circuit including switch means associated with the winding a, b, c for varying the current passing through the winding; rotor position sensing means arranged to sense the position of the rotor; control means arranged to provide drive signals to control the switch means; a power input for connection to a power supply at a nominal voltage; and boost means in electric communication with the power input and power output, and controllable to boost the nominal voltage to a higher voltage for application to the winding.

Abstract: A drive system for a three phase brushless AC motor that is operative to optimize a transistor switching pattern to improve power output while allowing current measurement in all of the phases using a single sensor. This is achieved by defining a voltage demand vector where more than two states are required to meet a minimum state time requirement determined by the single sensor and calculating three or more state vectors that produce the demand vector while still allowing single current sensing.

Abstract: A drive system for a three phase brushless motor uses an algorithm for position sensing which measures the inductance in the motor phases and determines the position from the measured inductances. In order to reduce acoustic noise, the inductances are measured during test periods Tsd, which are conducting states added to the PWM pattern in each PWM period. The test periods have net voltage of zero and therefore do not affect the output of the motor, but are sufficiently long to allow inductance measuring as well as the use of a single current sensor for current sensing.

Abstract: A switched reluctance generator is provided in association with a controller (86 to 90). The controller is organized to operate in two modes depending on the speed and load of the generator. One mode is a discontinuous conduction mode where the current is a generator winding periodically returns to zero, whereas the other mode is a continuous conduction mode such that current is always flowing. The choice of modes enables a generator to work over a wide speed range while seeking to limit or reduce the volt-amp rating of the generator controller.

Abstract: An aero-engine is provided with an integrated switched reluctance generator permanently connected to the low speed spool of the engine such that “windmilling” of the engine enables the generator to be turned if the engine suffers a flame out. The generator is driven by a step up gearbox so as to provide reasonable electrical output, say 25 kW, during flameout whilst keeping the generator weight down.

Abstract: An electric motor of the brushless type is disclosed which is so constructed and arranged as to provide a low braking torque. An electric power steering system incorporating such a motor is also disclosed. In a preferred arrangement, the motor comprises an interior permanent magnet motor. An advantage of providing a motor which generates low levels of braking torque in the event of a fault is that a driver can easily turn the wheel of the vehicle in the fault condition against the motor. This reduces the requirements for motor fault protection.

Abstract: A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state while the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds while at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

Abstract: A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state whilst the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds whilst at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

Abstract: An electric actuator for use in a vehicle power steering system includes an electric motor (20) and a gearbox (22). The electric motor (20) has a stator (26) and an armature (27) concentric with the stator (26) that is adapted to rotate about a common axis. A single common output shaft (40) extends through the actuator (14) to transmit torque from the motor (20) to a drive portion (70) of the output shaft (40) remote from the gearbox (22), from whence torque is transmitted to the gearbox (22) through a transmission portion (60) of the shaft (40). A clutch (21) may be provided between the motor (20) and the output shaft (40).