Abstract: A motor variator and a driving method thereof are provided for controlling the operating speed of a fan, which employ an alternate current chopper to change the working cycle and the rotary speed of a stepless motor. The motor variator includes a high-frequency alternate current chopper connected to an induction coil of an induction motor, an alternate current power supply connected to the high-frequency alternate current chopper and a controller connected to the high-frequency alternate current chopper for outputting a switch signal to the high-frequency alternate current chopper, such that the high-frequency alternate current chopper is controlled by the switch signal to perform a chopper action for the alternate current power supply and output a drive voltage, so as to change the rotary speed of the induction motor.

Abstract: A motor control device that can reduce electrical noise is provided. A motor control device includes an inverter, a current controller, a high frequency wave superpositioner, and a high frequency wave setter. An inverter applies a current to the motor. A current controller outputs a voltage to the inverter according to a current applied to the motor from the inverter. A high frequency wave superpositioner applies a high frequency wave to the voltage from the current controller as a superpositioned wave to infer a position of a rotor in the motor. A high frequency wave setter varies at least one characteristic of the superpositioned wave applied by the high frequency wave superpositioner.

Abstract: A voltage detection section and current detection section detect a voltage and current supplied to a motor, and the detected voltage and current are supplied to a position detection section. An angular speed output from the position detection section is supplied to a differentiator to output an angular acceleration. A fundamental wave component extraction section extracts a fundamental wave component of the angular acceleration, and the extracted fundamental wave component is supplied to an amplitude adjustment section. The output of the amplitude adjustment section is subtracted from the average current command by a subtraction section. This subtraction result, current detection value, and the rotor position from the position detection section are supplied to a current control section to carry out the current control operation so as to obtain a current command.

Abstract: An interrupt signal is generated at each of rising timings of PWM signals which are produced on the basis of phase-shifted triangular wave carrier signals for phases, and voltage command values for the phases. At timings of the interrupt signals, A/D conversion of motor currents of the phases detected by a shunt is started. Interrupt signals are also produced at timings of valleys of the triangular wave carrier signals. Additionally, peak interrupt signals and valley interrupt signals are respectively produced at timings of peaks and valleys of triangular wave carrier signals for phases. Based on each of the peak interrupt signals, normality/abnormality of a switching element of an upper side of the phase corresponding to the interrupt signal is checked, and, based on each of the valley interrupt signals, normality/abnormality of a switching element of a lower side of the phase corresponding to the interrupt signal is checked.

Abstract: System, method and apparatus for commutating a multiphase motor utilizing a single sensor. Commutation is carried out by employing a sensible system which incorporates phase commutating transition attributes. A motor is started by assigning a starting phase for a given direction of motor direction. An aligning phase initially is energized to orient the rotor so as to provide adequate starting phase start-up torque. Following such alignment and start-up, the motor is operated in response to transitions of the sensible system. In one aspect, a reference phase attribute may be incorporated in the sensible system to provide a mandated reference phase energization when the rotor is oriented for reference phase activation. Further described is a sensible system magnetic region configuration which is combined with a single package Hall effect sensor to provide three-phase unipolar and four-phase commutation with absolute phase defining information.

Abstract: An apparatus for driving a brushless motor and method of controlling the motor, which actively changes an output time of a phase commutation signal depending on variation of a load and stably operating the motor in an overloaded state and improving an operational efficiency of a system. The apparatus for driving a brushless motor includes an inverter, a driver, a counter-electromotive voltage detector and a controller. The inverter switches driving voltages applied to multi-phase stator coils. The driver drives the inverter. The counter-electromotive voltage detector detects a counter-electromotive voltage induced from an unexcited stator coil. The controller calculates a time required to detect a counter-electromotive voltage through the counter-electromotive voltage detector after the driving voltage is turned off, determines a phase commutation point of time based on the determined elapsed time, and controls the driver to perform phase commutation at the determined phase commutation time.

Abstract: A carrier wave frequency generating unit 9 modulates a frequency f of a carrier wave in a triangular shape. Occurrence of drawbacks due to the frequency f of the carrier wave can thereby be prevented. Because the frequency f of the carrier wave can be easily computed and estimated, a delay time of control, which is due to time for computing the frequency or an integration constant of PID control, can be kept to a minimum, and motor efficiency can be prevented from deteriorating. Because a control delay time can be estimated easily, it is possible to prevent carrying out of delay compensation by feed forward, and to prevent the motor efficiency from deteriorating.

Abstract: A non-invasive apparatus and method for measuring the speed of a rotating device that includes a sensor that measures a dynamic characteristic of the rotating device. A sample of the signal is transformed from the time domain into a frequency spectrum. The frequency spectrum is then analyzed to determine the motor speed. The resulting motor speed can be combined with other motor data by an order analysis to identify malfunctioning or improperly installed components.

Abstract: A resonance frequency detector for an electric motor controller in which a resonance frequency can be measured at high speed by a simple calculation and the resonance frequency can be detected by an inexpensive computer is provided.

Abstract: A circuit for recovering a current sense signal which is offset by a common mode displacement, such is the case when the signal is the voltage across a current sense resistor located on the high side bus or between the switches of a motor controller circuit. The circuit of the present invention converts the voltage across the resistor into a pulse code modulated (PWM) data, then downshifts the voltage, such that the signal of interest may be processed and recovered at the lower voltage for current feedback control purposes. The conversion of the measured current into a PWM signal is performed such that the PWM signal is synchronous with the motor PWM frequency. Although the output of the IC is synchronous with the motor PWM frequency, the output duty cycle is completely independent of the motor PWM duty cycle. In this way, the reconstructed sampled output of the IC is exactly equal to the fundamental motor current, without the effect of ripple current.

Abstract: A control system for an electric motor including an inverter for providing power to the electric motor, a controller for controlling the inverter, a first motor speed control block in the controller injecting a high frequency signal into the electric motor to determine the speed and position of the electric motor, where the first motor speed control block includes a tuned moving average filter to determine the magnitude of high frequency current in the electric motor.

Abstract: An operation control method of a reciprocating compressor is disclosed in which, in case that a motor is overloaded, an operation frequency is increased to render magnetic fluxes of a magnet and an input current are mutually offset, so that a reciprocating compressor can be stably driven even in case of the overload. For this purpose, while the reciprocating compressor using an inverter is operated at a rated frequency, a current load of the motor is measured and the measured load is compared with a pre-set reference load. Upon comparison, if the measured load is greater than the reference load, it is determined as an overload and the operation frequency is increased by as much as a certain value higher than an oscillation frequency, for performing an overload operation.

Abstract: A method for measuring the current in each phase of a three-phase motor (26) by the sensor (32), the motor (26) being controlled by a plurality of switching devices (S1-S6) that receive pulse width modulation signals from a controller (34). In one embodiment, a first and second sampling window (t1 and t2) are monitored. When both the first and second sampling windows (t1 and t2) are less than a minimum sampling window (mw), the voltage pulse trains associated with the highest output (V_h) and the lowest output (V_l) are shifted to form a first modified sampling window (t1′) and a modified second sampling window (t2′). When the first sampling window (t1) is less than the minimum sampling window and the second sampling window (t2) is greater than the minimum sampling window (mw), then the voltage pulse train associated with the highest output (V_h) and/or the middle output (V_m) may be shifted to form the first and second modified sampling windows (t1′ and t2′).

Abstract: A motor control apparatus comprises a fundamental current control device that controls a fundamental current in a 3-phase AC motor in an orthogonal coordinate system constituted of a d-axis and a q-axis rotating in synchronization with the rotation of the 3-phase AC motor, a higher harmonic current control device that controls a higher harmonic current in the motor in an orthogonal coordinate system constituted of a dh-axis and a qh-axis rotating at a frequency that is an integral multiple of the frequency of the fundamental component of the current flowing to the motor, an estimating device that estimates the level of the harmonic speed electromotive force in the motor in the dhqh-axis coordinate system and a compensating device that compensates the harmonic speed electromotive force estimated by the estimating device.

Abstract: The invention relates to a method for regulating an electrical machine (1) with an excitation winding (2) and a stator winding (3). The stator winding (3) is connected at its output terminals (10) to a converter bridge (5). The electrical machine (1) can be operated in the regulation ranges of field-oriented regulation (11), field-weakening operation (12), and diode operation (13). The transition from one of the regulation ranges (11, 12, 13) to a respective adjacent regulation range (11, 12, 13) is achieved through an overmodulation of the pulse-to-width modulation (26) and a limitation of the outputs from current regulators (34, 35) of the stator winding (3) of the electrical machine (1).

Abstract: A method for controlling a cooling arrangement for electronic components in a hybrid electric vehicle is disclosed. The method includes arranging an electronics cooling loop aboard a hybrid electric vehicle in which a DC to DC converter, DC to AC inverter, and an electronics radiator are placed in fluid communication, one with the others, for cooling the DC to DC converter and the DC to AC inverter; sensing a temperature condition in the electronics cooling loop; and discontinuing operation of the DC to DC converter when a predetermined upper threshold temperature condition is sensed in the electronics cooling loop. A voltage condition of a 12 volt battery may also be sensed, and operation of the DC to DC converter may be resumed when the voltage condition sensed falls below a predetermined lower voltage limit.

Abstract: An instruction value is added to a specific signal to produce an added signal. A servo motor is driven based on this added signal. The response of the motor is measured while the motor is being driven. A characteristic value calculated based on the response is compared with a reference value. When the characteristic value is significantly smaller than the reference value, the amplitude of the specific signal is changed so that the characteristic value converges to the reference value. When the characteristic value has almost converged to the reference value, frequency characteristics can be identified accurately.

Abstract: A method and apparatus for essentially eliminating cyclic disturbances in a motor control system, the method including identifying frequencies of undesirable components in a feedback signal that exceed a threshold level and generating a combined signal including sine wave components corresponding to each of the identified frequencies, delaying the combined signal to generate a plurality of identical but phase shifted combined signals, weighting each one of the delayed signals as a function of the magnitude of an instantaneous corrected signal which is the difference between a velocity error signal and a compensation signal and adding each of the weighted signals to generate the compensation signal.

Abstract: To provide a spindle motor control method adapted to an optical disk recording and reproducing apparatus capable of recording a signal onto a disk using a laser applied from an optical pick-up, a reference signal originated from a disk (1) and a reference signal necessary for signal recording are synchronized to each other when resuming signal recording once suspended. The synchronization is established without using a phase error component. Once synchronization is established, a phase error component is added to a servo signal of the spindle motor (2). A gain for a phase error component is begun gradually increasing after a phase error component is begun being added to a servo signal. An upper limit value of the gain of a phase error component to be added is determined depending on the location of a part on the disk (1) at which to resume the once suspended signal recording.

Abstract: In a chopping energization control device, a pair of switching elements IGBT/U and IGBT/L are used to control an electric power supplied from a DC power source to a phase coil CL1 of a DC motor, particularly an SR motor, such that one of the switching elements is alternately turned on-and-off while the other is being turned on continually. To avoid uneven heat generations between the switching elements, an arrangement is provided wherein whenever a time elapses beyond a limit value of, for example, 10 milliseconds the conditions of the respective switching elements are swapped with each other. Such a swapping is established cyclically which causes equal heat generations in the switching elements.

Abstract: A control unit is arranged for a synchronous motor formed of a rotor provided with a magnet. The control unit includes a 180°-conduction drive unit for performing 180°-conduction drive of the synchronous motor, a 120°-conduction drive unit for performing 120°-conduction drive of the synchronous motor, a rotation speed calculating unit for calculating the motor rotation speed, a rotation-speed-vs.-efficiency table unit storing an efficiency relative to a rotation speed of the motor, and a drive method selecting unit for selecting an optimum drive method for the current rotation speed based on the current rotation speed and information stored in the rotation-speed-vs.-efficiency table unit. Thereby, the synchronous motor performs 120°- or 180°-conduction drive in accordance with the current rotation speed to achieve the drive with an optimum efficiency.

Abstract: An electric power steering device constructed to detect a steering force by a driver and a vehicle speed respectively by a torque sensor and a vehicle speed sensor, set a steering force assisting current for a motor by a steering force assisting current setter using the detected steering force and the detected vehicle speed, set an upper limit value of a motor current by a motor current upper limit value setter based on a power function of a deviation between the set steering force assisting current and a predetermined motor current reference value, and perform overheat protection by setting an upper limit of a motor current applied by a motor driving circuit based on an integrated value of the motor current squared, whereby a problem of an insufficient steering assisting force when stationary steering is repeated many times while parking in a garage in a narrow parking area is solved.

Abstract: An optimal control system is described having multiple aspects. In one aspect, an arrangement is provided for eliminating integrator windup. This aspect includes forming a control difference signal that is a combination of differenced inputs and then subsequently integrating and limiting the control difference signal to form a control signal that is provided to the plant. In another aspect, an arrangement is provided for eliminating cross-channel coupling. In this aspect, an error signal is formed as the difference between a commanded signal and a regulator sensor signal. In addition, an injection error signal is combined with the error signal. The injection error is of an amount sufficient to ensure that only an attainable command signal is provided to the plant, without significant cross-channel coupling due to saturation of a control effector. In another aspect, an arrangement is provided for improving output mixing of the control signal between available plant effectors.

Abstract: A method and circuit are presented for operating a polyphase dc motor in which drive voltages are applied to the windings of the motor in predetermined phases. Zero crossings of currents flowing in respective windings of the motor are detected, and phases of the drive voltages are adjusted to have zero crossings substantially simultaneously with the detected zero crossings of the currents flowing in respective windings of the motor. The method includes generating a set of three waveforms (45,46,47) to provide drive voltages to respective windings of the motor. Each waveform has a period of 360° with a first segment (43) having a value of zero for 120°, followed by a second segment (50) having an “up slope” shape for 60°, followed by a third segment (67,68) having two consecutive “cap” shapes for 120°, followed by a fourth segment (52) having “down slope” shape for 60°. Each waveform of said set is displaced from one another by 120°.

Abstract: It is assumed that an element to be detected 2a in a position sensor is mounted on a rotary shaft with the center O′ of the element to be detected eccentric from a center of rotation O by a distance d. When the rotary shaft is rotated at a fixed speed, the positions at angles 0° and 180° are accurately detected by a sensor 2b, while the positions at angles 90° and 270°, the sensor detects the positions P1′ and P3′, instead of P1 and P3 which are originally to be detected, resulting in undulation of detected positions as shown in FIG. 3(b). The peak value of the unduration and an angle of rotation at which the peak value is found are determined.

Abstract: A method and apparatus for tuning control loop parameters in a motion control system, is provided. In one embodiment, tuning of the proportional and integral gains of a servocontroller's velocity loop compensator is provided, as well as tuning of the cutoff frequencies of the servocontroller's low pass filters. In this embodiment, random noise excitation is added to the velocity command during a plurality of movement types for a machine tool axis. During each movement type, frequency response measurements are taken. Then, a composite frequency response can be selected by concatenating portions of the various frequency response measurements, so as to simulate a worst case scenario for the machine tool axis. From this composite response, an open loop response can be calculated and displayed, as well as bandwidth, phase margin, and gain margin values. The user can then enter the compensator parameters which were used when this data was taken, as well as proposed parameters.

Abstract: An active attenuation system for a DC motor which yields global vibration reduction of slot or other motor induced tonals at the plate on which the motor is mounted without modifying the construction of the motor. The system comprises one or more vibration sensors, a signal synchronized to the slot rate or other motor induced tonal rate, an electronic adaptive controller and the means to supply the control signal into the motor field and/or armature current.

Abstract: A method and circuit are presented for operating a polyphase dc motor in which substantially sinusoidal drive voltages are applied to the windings of the motor in predetermined phases. Zero crossings of currents flowing in respective windings of the motor are detected, and phases of the drive voltages are adjusted to have zero crossings substantially simultaneously with the detected zero crossings of the currents flowing in respective windings of the motor. The method and circuit results in motor operation with significantly reduced acoustic motor noise.

Abstract: The absolute position of a rotor of a permanent magnet motor is determined by detecting an angular position of a direct axis of the rotor; and detecting a polarity of the rotor to determine the absolute position of the rotor. The polarity of the rotor may be determined by applying a square wave voltage to phase windings of a stator of the motor to generate an mmf vector parallel to the direct axis, measuring phase currents of the phase windings, determining a direct axis current responsive to the measured phase currents and the angular position, determining that the rotor is aligned with the mmf vector if the direct axis current is shifted positive, and determining that the rotor is aligned 180 degrees out of phase with the mmf vector if the direct axis current is shifted negative.

Abstract: A magnetic bearing wherein a stator is magnetically interacted with a rotor and is movable in response to feed-back of rotor position to thereby use the magnetic interaction between the stator and rotor to effect movement of the rotor toward a predetermined rotor position for bearingly controlling the rotor position. The bearing may be a radial or thrust bearing.

Abstract: A method of detecting phase error between a phase current and a driving voltage includes generating a signal indicative of the phase current. The method includes identifying a time interval during which the signal indicative of the phase current is generally symmetric about a midpoint of the time interval when the phase error is approximately zero. The method further includes determining the extent to which the signal indicative of the phase current is symmetric about the midpoint of the time interval. Finally, in response to determining the extent to which the signal indicative of the phase current is symmetric, the method includes generating phase error information.

Abstract: A method and apparatus for substantially reducing tonal noise and or vibration generated by a rotating machine. The power supplied to the rotating machine or motor drive signal is modulated as a function of time so that the shaft rate of the rotating machine is varied as a function of time. The motor drive signal or power signal can be modulated in an alternating current (AC) machine wherein the shaft rate is related to the power line frequency, as well as a direct current (DC) machine wherein the shaft rate is related to the DC level applied, to alter the shaft rate as a function of time. Such drive power modulation causes the drive signal energy to spread into new frequencies. As a result, the radiated tonal components are spread out such that the strength of the rotating machine's tonal radiation is substantially reduced. In addition, "beating" effects related to the operation of multiple machines can be reduced.

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 rising saw tooth signal generating circuit generates a rising saw tooth signal having a constant amplitude and a constant period which corresponds to a frequency being slightly higher than the human audible frequency range. The rising saw tooth signal generating circuit also generates a binary signal which generates a reference chopping timing synchronizing with the rising saw tooth signal. The rising saw tooth signal is inverted and a descending saw tooth signal is generated. The descending saw tooth signal is added to the reference current signal and a binary signal is generated by the result of the comparison between the addition signal and the actual current signal. A flip-flop generates a signal which reaches a low level whenever the binary signal is descended and which reaches a high level whenever the reference chopping timing comes. A further binary signal which moves to the high level at the feeding of the current and the signal are supplied to the AND gate.

Abstract: A time-discrete phase-locked loop includes a discrete time oscillator (DTO) which supplies a periodical oscillator signal (OS) representing oscillator values (OV) at corresponding clock instants (TC) of a clock signal (CLK). A position-determining circuit (P) generates a time-discrete synchronization instant (SI) representing a position of an analog synchronizing pulse (SP) of a video signal with sub-clock period accuracy. A phase detector (PD) determines a phase error (PE) between the discrete time oscillator signal (OS) and the synchronization instant (SI) by using the synchronization instant (SI), a value (OV1) of the discrete time oscillator signal (OS) at a clock instant (TC1) related to the synchronization instant (SI), and the slope of the oscillator signal (OS). A period of the oscillator signal (OS) depends on the phase error (PE). By using the slope of the oscillator signal (OS), the phase error (PE) is independent of this slope.

Abstract: The known arrangements have at least one rotor coil (RS) arranged on the rotor and at least one stator coil (SS) arranged on the stator. The rotor coil (RS) and the stator coil (SS) respectively have at least one winding (WI) and there is a magnetic coupling between the rotor coil (RS) and the stator coil (SS). With an arrangement of this sort, it is possible for example to transmit measurement signals of a measurement pickup (MA) arranged on the rotor (RO) for the contactless measurement of torques. The additional acquisition of the respective angular position and/or of the respective angular speed (.omega.

Abstract: A motor control circuit controls a motor in a disc drive. The motor control circuit includes a voltage controlled oscillator (VCO) providing a commutation timing signal. A commutation circuit is operably coupled to the VCO and provides commutation signals to the motor based on the commutation timing signal. A phase locked feedback circuit is operably coupled to the commutation circuit and provides a feedback signal to the VCO based on a sensed commutation phase to control a frequency of the commutation timing signal. A modulator is operably coupled to the phase locked feedback circuit and modulates the feedback signal. A method is also provided in which the commutation timing signal is modulated so as to spread a frequency spectrum of the commutation signals.

Abstract: A motor control circuit controls a motor in a disc drive is provided. The motor control circuit includes a commutation circuit which provides commutation signals to the motor to commutate the motor at a commutation frequency. A frequency modulation circuit is operably coupled to the commutation circuit. The frequency modulation circuit provides a modulation signal which frequency modulates the commutation frequency according to a predetermined pattern.

Abstract: An adaptive feedforward control system for reducing noises during a track seek operation. A servo control apparatus of the invention generates a first adaptive feedforward, in which the first adaptive feedforward adaptively follows a current command for servo-controlling the hard disk drive at a servo control decelerating interval for the track seek, and the first adaptive feedforward has a linear slope. Further, a high frequency component is removed from the first adaptive feedforward. Therefore, it may be possible to remove the current control error as well as the noises during the track seek operation.

Abstract: An apparatus has a mass suspended between two mounting plates by a separate springs to form a resonant structure that absorbs vibration in a structural member to which the mounting plates are attached. Permanent magnets are fixed to opposite sides of the mass. A sensor produces a signal indicating the frequency of the vibration. A feedback circuit receives the signal from the sensor and produces an output signal having first component frequency which corresponds to a harmonic of the frequency of the vibration. The output signal is applied to a separate voice coil adjacent to each permanent magnet. The magnetic fields produced by the output signal flowing through the voice coils interact with the magnetic fields from the permanent magnets to generate forces that act on the mass in a manner that increases the impedance of the absorber to the vibration in the structural member.

Abstract: A differential amplifier amplifies a PG reproduction signal to a level permitting signal processing. A low-pass filter makes the signal waveform of a PG detection signal generated by the differential amplifier substantially uniform irrespectively of the rotational speed of a rotating drum. A comparator outputs a PG pulse by comparing an output of the low-pass filter with a threshold. A magnetic recording and reproducing apparatus having such a structure can detect the PG pulse with accuracy over a rotational speed range requiring a precision control of the rotating drum.

Abstract: A master-slave synchronization control system is constructed having two drive systems for driving respective ones of two controlled objects capable of being operated individually, wherein the drive system having the slower response is adopted as the master and the drive system having the higher response is adopted as the slave. The drive system of the master, which has the elements of a velocity control system that operates to follow up an entered velocity command value, outputs velocity information and position information of its controlled object. The drive system of the slave has a velocity control system in which the velocity information is adopted as the velocity command value, and a position compensating loop in which the position information is adopted as a position command value. The position compensating loop adds the position compensation value to the velocity command value as a correction signal.

Abstract: An electrical drive control system includes a controlled drive, an auxiliary generator, a control unit, and a power unit. The rotors of the controlled drive and of the auxiliary generator are connected so that rotation of controlled drive causes a corresponding rotation of the auxiliary generator. The control unit receives a first reference signal having a first frequency. The auxiliary generator receives a second reference signal having a second frequency. The control unit may generate the second reference signal. In response to the second reference signal, the auxiliary generator generates a primary information signal having a phase shift that is indicative of the rotational position of a rotor of the auxiliary generator and the controlled drive. The control unit receives a user selected position command indicative of a selected position of the rotor.

Abstract: A method of amplifying the torque output by an electric torque motor (10) of a system such as a vehicle electronic throttle control system. Upon the formation of ice on and around the throttle plate (T) of an electronic throttle system, the torque output by the torque motor (10) connected to rotate the throttle plate (T) is amplified from a normal operating torque to an amplified torque sufficient to overcome the ice or other obstruction. The method includes applying either a clockwise or counter-clockwise direction torque to the rotor (38) of the torque motor (10) to twist the output shaft (34) connected to the stuck throttle plate (T). The torque applied to the rotor (38) is then reversed so that the other of the clockwise and counter-clockwise direction of torque is applied to the rotor (38). The foregoing torque-application steps are repeated in succession at a select frequency equal to the natural frequency of the mechanical system of which the motor (10) and throttle plate (T) are parts.

Abstract: An actuator controller using a periodic signal includes: an actuating unit for moving a movable portion with respect to a fixed portion by a predetermined amount; a drive unit for operation the movement; a power supply unit for supplying an electric power to the drive unit; and a periodic signal generating unit, which includes a velocity command signal generating part for generating a velocity command signal on the basis of an output of the movable portion, and a driving frequency calculating part for determining the frequency of the periodic signal in accordance with the velocity command signal.

Abstract: In a rotation detection apparatus, a magnetism pattern section provided with plural magnetic poles and a FG (frequency generating) pattern section provided with plural toothed wire circuits are located so as to face each other. When either one of the magnetism pattern section and the FG pattern section is rotated together with a rotating member, plural wave signals are electrically induced in the plural toothed wire circuits. A signal processing cicuit synthesizes the plural wave signals so as to output a multiplication signal and detects the rotation of the rotating member based on the multiplication signal.

Abstract: A disk drive including firmware for overcoming stiction and breaking free the heads of a disk drive which may adhere to the disk surface when the disk is at rest. Upon start-up of the disk drive, if stiction at the head/disk interface occurs, the voltage to the spindle motor and/or actuator motor may be rapidly fluctuated so as to cause a pulsing of the spindle motor and/or actuator motor. Pulsing both the spindle motor and actuator motor creates forces in a plurality of radial directions to allow the head(s) to break free from the disk(s) in the direction of least resistance. Moreover, as the resonant frequency of the spindle motor varies depending on the number of heads that are stuck, the firmware pulses over a range of frequencies including the various resonant frequencies of the spindle motor corresponding to various numbers of heads stuck.

Abstract: The present invention relates to an AC servo motor control is disclosed, in which a voltage command is produced from the deviation between a current command and feedback current for the AC servo motor control according to the voltage command thus produced. Whenever the voltage command becomes zero, feedback-current data is collected for a predetermined period of time. Offset amount is calculated for updating according to the collected feedback-current data. Subsequently, the feedback current is corrected by using the new offset amplitude during revolution of the AC servo motor. A voltage command to the AC servo motor is produced according to the deviation between the current command and the compensated feedback current.

Abstract: An apparatus for controlling the output and torque of a synchronous alternator has a controlled bridge rectifier operable off synchronous for rectifying the alternating output and establishing a desired phase relationship between the alternating voltage and alternating current of the output winding. Phase locked loop control may be employed for establishing and maintaining a desired phase relationship to control the output and torque.

Abstract: A current control method for a servo motor capable of compensating a delay in a current loop. A corrective electrical angle corresponding to the delay in the current loop is obtained and a phase angle is corrected using the corrective electrical angle. Then the delay of the current loop is compensated by a DQ coordinate conversion for converting a three-phase AC current into a two-phase DC current, or a two-phase DC voltage into a three-phase AC voltage, using the corrected phase angle. The phase angle is corrected by subtracting the corrective electrical angle from the phase angle and the DQ conversion is performed for obtaining a two-phase DC current from a three-phase AC current using the corrected phase angle. Alternatively, the phase angle is corrected by adding the corrective electrical angle to the phase angle and the DQ conversion is performed for obtaining a three-phase AC voltage from a two-phase AC voltage using the corrected phase angle, to compensate the delay of the current loop.