Abstract: A control technology for a synchronous motor for suppressing rotational pulsation caused by variation in individuals without making a control algorithm complex is provided. In a motor drive system which is a control device for a synchronous motor, in order to suppress the pulsation component of N times as high as the AC frequency for driving the synchronous motor, a controller in which the phase property of the disturbance response of the controller with respect to the pulsation frequency is within ±45° is arranged. Therefore, the torque pulsation component generated from distortion in induction voltage or variation between phases is suppressed.

Abstract: A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

Abstract: A dc motor drive system with a PWM control system permits a high-accuracy rotation drive control while detecting the currents flowing into the coils without using shunt resistors. The system drives output MOS transistors by the PWM control to make the currents flow into the coils, and drives to rotate the dc motor. The system includes current sensing MOS transistors having a predetermined size ratio 1/m (M>1) to the output MOS transistors that make the currents flow into the coils. The current sensing MOS transistors are capable of making flow reduced currents proportional to the currents of the output MOS transistors.

Abstract: A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

Abstract: A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

Abstract: In start-up control of a motor in which currents are caused to flow through any two of three phase coils to detect the polarity of a voltage induced in each de-energized phase, thereby determining the corresponding energized phase at start-up thereof, based on the polarity of the detected induced voltage, the levels of induced voltages are detected in addition to the polarity of the induced voltage for the de-energized phase to thereby determine the relationship between the magnitudes thereof, and the energized phase at the start-up is determined based on the relationship of magnitude between the polarity of each induced voltage and the level thereof.

Abstract: A drive control device of motor capable of starting up even a motor of such a type that the polarity of induced voltage does not switch every 180° of electrical angle or the polarity, positive or negative, does not occur with accuracy without causing a reverse rotation is provided. In a start-up control of motor, the following operation is performed: a current is passed through any coils in two phases, and the polarity of voltage induced in the non-conducting phase is detected. A conducting phase at start-up is determined based on the detected polarity of induced voltage. The average value of induced voltages in non-conducting phase detected with respect to the coils in respective phases is determined. The average value and the detected induced voltages are compared with each other, and relative polarities are determined from the magnitude relation with the average value to determine a conducting phase at start-up.

Abstract: A motor drive device which controls a spindle output predriver unit and power MOSFETs of an output stage associated with it to form a PWM signal in such a manner that a detection current formed by a DC shunt resistor and a sense amplifier and a current instruction signal coincide with each other, generates a regenerative signal obtained by giving dead times to the PWM signal, generates an energizing timing signal from the result of BEMF (back electromotive voltage) zero cross detection and generates signals for controlling on/off of power MOSFETs of three phases to thereby drive a three-phase motor, is provided with a switching characteristic adjustment unit which measures a time at which the spindle output is being transitioned and performs such feedback control that the measured time and a designated switching time coincide with each other.

Abstract: In a magnetic disk memory device, the shifting speed of the magnetic head in time of power supply interruption is detected, and a voice coil motor is controlled in accordance with the detected shifting speed to enable the head to be shunted safely and promptly.

Abstract: A motor drive device which controls a spindle output predriver unit and power MOSFETs of an output stage associated with it to form a PWM signal in such a manner that a detection current formed by a DC shunt resistor and a sense amplifier and a current instruction signal coincide with each other, generates a regenerative signal obtained by giving dead times to the PWM signal, generates an energizing timing signal from the result of BEMF (back electromotive voltage) zero cross detection and generates signals for controlling on/off of power MOSFETs of three phases to thereby drive a three-phase motor, is provided with a switching characteristic adjustment unit which measures a time at which the spindle output is being transitioned and performs such feedback control that the measured time and a designated switching time coincide with each other.

Abstract: A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

Abstract: A dc motor drive system with a PWM control system permits a high-accuracy rotation drive control while detecting the currents flowing into the coils without using shunt resistors. The system drives output MOS transistors by the PWM control to make the currents flow into the coils, and drives to rotate the dc motor. The system includes current sensing MOS transistors having a predetermined size ratio 1/m (M>1) to the output MOS transistors that make the currents flow into the coils. The current sensing MOS transistors are capable of making flow reduced currents proportional to the currents of the output MOS transistors.

Abstract: In start-up control of a motor in which currents are caused to flow through any two of three phase coils to detect the polarity of a voltage induced in each de-energized phase, thereby determining the corresponding energized phase at start-up thereof, based on the polarity of the detected induced voltage, the levels of induced voltages are detected in addition to the polarity of the induced voltage for the de-energized phase to thereby determine the relationship between the magnitudes thereof, and the energized phase at the start-up is determined based on the relationship of magnitude between the polarity of each induced voltage and the level thereof.

Abstract: In a magnetic disk memory device, the shifting speed of the magnetic head in time of power supply interruption is detected, and a voice coil motor is controlled in accordance with the detected shifting speed to enable the head to be shunted safely and promptly.

Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

Abstract: A surface acoustic wave actuator is disclosed which includes unidirectional interdigital transducers disposed on both sides of a vibrator and an electrical combiner. One of the unidirectional interdigital transducers and external power supply are connected to an input port, and the other unidirectional interdigital transducer is connected to an output port of the electrical combiner. The electrical combiner combines input energy from an external power supply and surface acoustic wave energy is electrically converted by one of the unidirectional interdigital transducers, and input to the other unidirectional interdigital transducer. Surface acoustic waves excited by the other unidirectional interdigital transducer propagates on a vibrator, and is input to the other unidirectional interdigital transducer again after passing one unidirectional interdigital transducer and the electrical combiner.

Abstract: An elastic surface wave gyroscope includes two transducers attached on a piezoelectric substrate to generate elastic surface waves having different frequencies on the piezoelectric substrate, and two pair of reflectors for reflecting the different elastic surface waves toward the generators to produce two different standing waves, and another pair of reflectors for reflecting an elastic surface wave caused by a Coriolis force to produce a third standing wave, and a detector for detecting an electric signal corresponding to the third standing wave. This gyroscope has a high detection sensitivity.