Abstract: A spindle motor can suppress the generation of noise during swinging and the extend service life, and also suppress the increase in current consumption. The outside diameter of a thrust hydrodynamic groove is at least 10% of the outside diameter of a disk-shaped medium, and the depth of the radial hydrodynamic groove is greater than the depth of the thrust hydrodynamic groove. By adjusting to specific numbers, the angular stiffness in the thrust bearing is raised, and even if a disturbance torque should be applied, wear or noise caused by metal contact inside the bearing can be suppressed.

Abstract: A spindle motor can suppress the generation of noise during swinging and the extend service life, and also suppress the increase in current consumption. The outside diameter Do of a thrust hydrodynamic groove 3 is at least 10% of the outside diameter Dd of a disk-shaped medium 20, and the depth of the radial hydrodynamic groove is greater than the depth of the thrust hydrodynamic groove. By adjusting to specific numbers, the angular stiffness in the thrust bearing is raised, and even if a disturbance torque should be applied, wear or noise caused by metal contact inside the bearing can be suppressed.

Abstract: There is provided a hydrodynamic bearing device having a communicating hole and with a bearing structure such that lubricant tends not to flow out of the bearing openings of the hydrodynamic bearing device even when the hydrodynamic bearing device is subjected to a large impact, as well as a spindle motor in which this hydrodynamic bearing device is installed. A hydrodynamic bearing device has a shaft and a sleeve that rotatably supports the shaft. A thrust flange is formed at one end of the shaft, is equipped with a protrusion that is opposed to a stepped component of the sleeve in the axial direction, and is configured such that the thrust flange does not block a communicating hole when an impact is applied, which suppresses the generation of a cavity near the thrust flange.

Abstract: A method for position-sensorless motor control is provided, wherein a rotor-position estimation current signal is superimposed on the &ggr;-axis direction component of a target current vector representing target currents of stator windings. The period of the current signal is an even multiple of a PWM carrier period and varies at random. The amplitude of the current signal increases with the amplitudes of the target currents. An even number of samples are obtained from the &dgr;-axis direction component of a current vector representing detected currents of the stator windings in each period of the current signal. A discrete Fourier integration of the samples determines the amplitude of a current response to the current signal in the &dgr;-axis direction. The &ggr;-axis direction is corrected so that the current response substantially shrinks to zero in the &dgr;-axis direction.

Abstract: A position sensorless motor control apparatus is provided that achieves high resolution and high accuracy angle estimation, achieves angle estimation even in the presence of phase voltage saturation, and achieves high accuracy angle estimation even when a back electromotive force constant changes. An angle estimating unit which generates estimated rotor angle comprises: an estimation phase selecting unit for selecting an estimation phase designating the stator winding phase to be used for the generation of the estimated angle; a deviation generating unit for generating, based on the estimated angle and phase voltage value, a deviation relative to a model expressed by a phase voltage equation of the estimation phase; an angle correcting unit for correcting the estimated angle so that the deviation converges to zero; and an estimated coefficient value correcting unit for correcting an estimated coefficient value which is the estimated value of a coefficient in the phase voltage equation.

Abstract: A method and an apparatus for position-sensorless motor control are provided, wherein an undesired sound is reduced and the S/N ratio in a detection of a current response to a rotor-position estimation signal increases without control delay, in contrast to the prior art, especially when a rotor is at a stop or slowly revolves. In the position-sensorless motor control method according to the invention, a rotor-position estimation current signal is superimposed on the &ggr;-axis direction component of a target current vector, which represents target currents of stator windings. The period of the rotor-position estimation current signal is an even multiple of a PWM carrier period, and varies at random. Furthermore, the amplitude thereof increases along with increasing of the amplitudes of the target currents.

Abstract: A motor control apparatus and a motor unit having such a motor control apparatus according to the present invention are constructed to detect a terminal voltage for switching elements of the same phase in a dead time period by a voltage output circuit 10, and to detect the instant when the sign of a phase current changes from the detected terminal voltage by a current sign change detection part 11. Based on the phase of a current sign change timing provided from the current sign change detection part 11 and the phase of a phase applied voltage, the first applied voltage control circuit 14 generates a phase applied voltage command to a switching element modulation circuit 9. Such arrangement makes it possible to provide motor continuous energization or motor energization drive near to 180 degrees at high efficiency, without the provision of any current sensors.

Abstract: A motor controller according to the present invention is so configured that time interval measuring means measures the time interval of a rotational position signal indicating the rotational position of a rotor based on said rotational position signal, correction coefficient storage means stores the correction coefficient indicating the inaccuracy of said rotational position signal, estimated rotational angle production means produces an estimated rotational angle providing an estimated value of the rotational angle by extrapolating the rotational angle based on said time interval and said correction coefficient, and command production means produces a current command or a voltage command based on said estimated rotational angle and outputs it to driving means for driving a motor.