Abstract: A method for determining an effective resistance of a voltage controlled DC motor having a nominal resistance includes driving the DC motor with a signal so that the DC motor has a targeted acceleration, and sensing an effective acceleration of the DC motor. The effective resistance of the DC motor is determined as a function of the nominal resistance, the targeted acceleration and the effective acceleration.

Abstract: A method for estimating resistance of a DC motor for positioning read/write heads of a data storage disk is provided. The DC motor is controlled in an open-loop voltage mode through a motor controller input with a first signal for compensating positioning of the read/write heads onto the data storage disk. The first signal is generated based upon a position error signal representing a difference between a position of the read/write heads and a center of a track to be read. The method includes monitoring the first signal during a read operation of data being stored on the data storage disk, and estimating the resistance based upon spectral components of the first signal.

Abstract: The present invention refers to a digital apparatus suitable for driving a load. The apparatus an input for receiving a voltage signal varied by an external disturbance and comprises means for sampling at least the external disturbance such as noise, and a driving circuit such as a pulse width modulator for driving the load with a suitable output voltage. The apparatus includes a control circuit suitable for generating digital commands representative of a desired output voltage of the apparatus. The apparatus also comprises digital correction circuit suitable for generating a correction signal on the basis of the difference between the value of the current sample and the value of the previous sample of at least the external disturbance. The output of the driving circuit is governed by the correction signal.

Abstract: A method for estimating resistance of a DC motor for positioning read/write heads of a data storage disk is provided. The DC motor is controlled in an open-loop voltage mode through a motor controller input with a first signal for compensating positioning of the read/write heads onto the data storage disk. The first signal is generated based upon a position error signal representing a difference between a position of the read/write heads and a center of a track to be read. The method includes monitoring the first signal during a read operation of data being stored on the data storage disk, and estimating the resistance based upon spectral components of the first signal.

Abstract: A driving circuit of a DC motor includes a control circuit for providing a control signal, and a motor drive circuit commanded by the control circuit for providing respective command signals for the switches of an output power stage connected to the DC motor. The output power stage is connected to a power supply line and drives the windings of the DC motor. The driving circuit prevents generation of voltage surges having a significant magnitude on the power supply line because the driving circuit has logic circuits for preventing any substantial inversion in the direction of current flow in the supply lines when the DC motor operates as a current generator.

Abstract: A method for determining an effective resistance of a voltage controlled DC motor having a nominal resistance includes driving the DC motor with a signal so that the DC motor has a targeted acceleration, and sensing an effective acceleration of the DC motor. The effective resistance of the DC motor is determined as a function of the nominal resistance, the targeted acceleration and the effective acceleration.

Abstract: The driving voltage of the motor is incremented a quantity proportional to the speed of the motor according to a proportionality factor that is adjusted to compensate the back electromotive force. A method includes open-loop voltage control of a DC motor having a certain design speed constant, through a driving signal that is determined for imparting a certain acceleration to the motor and by generating a driving voltage of an output power stage to which the winding of the motor is connected as a function of the driving signal.

Abstract: A transconductance amplifier for inductive loads and a relevant inductive load driving method, the amplifier having an input stage receiving a driving signal (set-point), a power stage connected downstream of the input stage and connected to the load and an output stage fedback on the input stage to transfer a signal associated to the load. Advantageously, the input stage comprises at least a comparator receiving on one input the driving signal and on another input the output of the output stage. A delay block is also provided between the comparator output and the power stage to delay the comparator switching. This can be obtained also by using a hysteretic comparator.

Abstract: A method for detecting the position of a rotor of a DC motor with N phases having a plurality of windings, comprising the steps of connecting two of the windings between first and second prefixed voltages through to a first current path for a prefixed time, allowing the current stored in the two windings to discharge through a second current path; comparing the voltage across one of the two windings with a reference voltage and providing a control signal when the voltage is smaller in absolute value than the reference voltage, performing the above steps for each of the winding pairs of the motor; detecting the position of the rotor on the basis of the control signals obtained.

Abstract: The present invention relates a Pulse Width Modulation (PWM)/linear driver for an electromagnetic load by a bridge circuit of the type having a signal input and a signal output and at least two conduction control inputs for driving a voice coil motor in a linear mode and in a pulse width modulation. The bridge circuit is driven by a PWM converter coupled to one of said two control inputs and by a linear amplifier coupled to the other of said two control inputs.

Abstract: The present invention relates to a method and a circuit using the method thereof for minimising the phase errors during the driving of an electric motor, and a circuit using the method thereof, having a stator winding, a permanent magnet rotor assembly, and devices able to sense a rotor position, which comprises the following steps: a) generating of a rotor position signal (10, 14, 39), by means of said devices able to sense said rotor position; b) detecting at least two information from at least two edges (11, 12; 15, 16) of said rotor position signal (10, 14, 39) inside a measure period; c) generating a driving signal (9, 13, 38), in function of said at least two information (11, 12; 15, 16) inside the measure period, so as to follow the rotor velocity.

Abstract: A transconductance amplifier for inductive loads and a relevant inductive load driving method, the amplifier having an input stage receiving a driving signal (set-point), a power stage connected downstream of the input stage and connected to the load and an output stage fedback on the input stage to transfer a signal associated to the load. Advantageously, the input stage comprises at least a comparator receiving on one input the driving signal and on another input the output of the output stage. A delay block is also provided between the comparator output and the power stage to delay the comparator switching. This can be obtained also by using a hysteretic comparator.

Abstract: A method for detecting the position of a rotor of a DC motor with N phases having a plurality of windings, comprising the steps of connecting two of the windings between first and second prefixed voltages through to a first current path for a prefixed time, allowing the current stored in the two windings to discharge through a second current path; comparing the voltage across one of the two windings with a reference voltage and providing a control signal when the voltage is smaller in absolute value than the reference voltage, performing the above steps for each of the winding pairs of the motor; detecting the position of the rotor on the basis of the control signals obtained.

Abstract: A driving circuit of a DC motor includes a control circuit for providing a control signal, and a motor drive circuit commanded by the control circuit for providing respective command signals for the switches of an output power stage connected to the DC motor. The output power stage is connected to a power supply line and drives the windings of the DC motor. The driving circuit prevents generation of voltage surges having a significant magnitude on the power supply line because the driving circuit has logic circuits for preventing any substantial inversion in the direction of current flow in the supply lines when the DC motor operates as a current generator.

Abstract: The present invention relates to a method and a circuit using the method thereof for minimising the phase errors during the driving of an electric motor, and a circuit using the method thereof, having a stator winding, a permanent magnet rotor assembly, and devices able to sense a rotor position, which comprises the following steps: a) generating of a rotor position signal (10, 14, 39), by means of said devices able to sense said rotor position; b) detecting at least two information from at least two edges (11, 12; 15, 16) of said rotor position signal (10, 14, 39) inside a measure period; c) generating a driving signal (9, 13, 38), in finction of said at least two information (11, 12; 15, 16) inside the measure period, so as to follow the rotor velocity.

Abstract: A method for detecting a zero-cross event of an induced back electromotive force (BEMF) or of a nullification instant of a periodic current in a PWM driven winding, by circuits generating an analog signal representative of the induced BEMF or of the nullification instant of the periodic current, comparing the analog signal with zero and producing a first logic signal, generating a PWM driving signal, and storing a time between two consecutive zero-cross events, is provided. The method may include storing a time between a last two zero-cross events and synchronizing the PWM driving signal from a last zero-cross event having a duration equal to a difference between an established time based upon the stored time interval and a first time. If a new zero-cross event is not detected within the established time, switching of the PWM driving signal may be disabled for a time having a maximum duration equal to a second time or until a new zero-cross event is detected.

Abstract: A start-up routine is provided for a multiphase brushless DC motor having one or more rotor position sensors insufficient to provide for an angular resolution as high as the angular resolution of the synchronized driving system of the motor. The start-up routine includes setting at least an angular check zone having a certain arc length angularly correlated to the one or more rotor position sensors, assuming a certain initial rest position of the rotor, and exciting for fixed time intervals the phase windings in a sequence for rotating the rotor toward an angular position next to the initial position. This routing is performed in the desired direction while masking the signals from the one or more rotor position sensors for a preestablished masking time.

Abstract: A method of detecting the relative position of the rotor of a sensorless DC brushless motor driven in a tripolar mode includes the step of monitoring the voltage difference between the drive voltage that is applied to at least one winding of the motor and the voltage drop on a resistive portion of the drive current path through the same winding. The voltage drop may be detected between the two current terminals of an MOS power device of the driving bridge of the winding. The monitoring of the voltage difference is used to signal a perturbation from a pre-existing condition of correct synchronization of the phase switchings during a driving phase in a tripolar mode of the motor. Such information may be used by the driving system to switch to one of a bipolar mode, a unipolar mode or a tripolar mode with momentary drive interruptions, until restoring a correct synchronization condition and/or attain a correct rotating speed.

Abstract: A method and system produce a PWM signal using a comparator having first and second input terminals and an output terminal at which the PWM signal is produced. The method includes powering the comparator with a supply voltage and receiving a modulating signal at the first input terminal. The method creates a carrier signal with a constant frequency and a maximum amplitude equal to the supply voltage. The comparator receives the carrier signal at the second input terminal and compares the carrier signal to the modulating signal, thereby producing the PWM signal at the output terminal. By creating and using a carrier signal with a maximum amplitude equal to the supply voltage, the PWM signal produced by the method is immune from changes in the supply voltage.

Abstract: A method is for driving a multiphase brushless motor with N windings connected in a star or in a polygonal configuration. The windings are driven according to a certain periodic voltage profile. The method includes cyclically keeping for a certain time interval at least one of the N windings in a fixed state of low or high saturation and applying to the other phase windings instantaneous voltages according to a predefined different periodic voltage profile such that the resultant voltages on the windings are coherent with the certain periodic voltage profile. The number of intervals, in an entire electrical period, in which the fixed high or low saturation state of one winding is produced, depends on the predefined driving profile and upon the number N of windings of the motor.