Abstract: A circuit for controlling an electromechanical holding brake, includes: at least one halfwave rectifier, which generates a pulsed DC voltage from a mains AC voltage, and a phase gating circuit which is designed to generate a control signal for the electromechanical holding brake from the pulsed DC voltage by means of the phase gating.

Abstract: In a drive system and method for operating a drive system, in which the drive systems includes an electromagnetically operable brake, an electric motor, e.g., a three-phase motor, and an electronic circuit, the brake has an energizable coil, e.g., a brake coil, the electronic circuit has a rectifier, an upper controllable semiconductor switch, a freewheeling diode, and a varistor, a direct voltage provided by a rectifier is able to be made available by closing or by a pulse-width-modulated actuation of an upper controllable semiconductor switch of the coil, and by opening the upper controllable semiconductor switch, a current driven by the coil in the de-excitation of the coil is freewheeling and/or flowing through the freewheeling diode and the varistor or through a component connected in parallel with the varistor.

Abstract: The invention relates to an electric brake system (1) for a vehicle. The electric brake system (1) comprises electric brake devices (2). The electric brake devices (2) are powered and controlled by redundant capacitor-based power sources (9A, 9B) and redundant control circuits (16A, 16B). The capacitor-based power source (9A, 9B) can be integrated into axle modules (39A, 39B) located close to a vehicle axle (61A, 61B). The capacitor-based power sources (9A, 9B) are recharged by a hub generator, a regeneration power source (32).

Abstract: A wireless sensing device disposed a drum along with laundry to measure humidity in the drum, thereby increasing accuracy in estimation of a degree of dryness, a dryer for determining a degree of dryness of the laundry using the wireless sensing device, and a method of controlling the dryer. The wireless sensing device includes a sensing module including a humidity sensor for measuring humidity in a drum of a dryer into which the wireless sensing module is thrown; a sensor communication module transmitting or receiving data with a main communication module of the dryer through wireless communication; a sensor controller configured to control the sensor communication module to transmit a humidity value corresponding to an output of the sensing module to the main communication module; and a sensor power supplier supplying power to the sensing module, the sensor communication module, and the sensor controller.

Abstract: In a control method by a robot system, in the robot system including a plurality of robots and a teaching device connected to the plurality of robots via a network, the teaching device transmits, to an identification act execution robot among the plurality of robots, an identification act instruction signal for causing the identification act execution robot to perform an identification act of identifying a transmission target robot to which operation data is planned to be transmitted among the plurality of robots, the identification act execution robot, which receives the identification act instruction signal, performs the identification act, and, after the identification act execution robot performs the identification act, when the identification act execution robot and the transmission target robot are the same, the teaching device transmits the operation data to the transmission target robot.

Abstract: A motor arrangement comprising: motor having a rotor, a stator, and a plurality of windings mounted on one of the rotor and the stator for acting on the other of the rotor and the stator, and a plurality of inputs coupled to the windings; and control circuit configured to operate in a riving mode in which it dynamically energises the windings via the motor inputs so as to cause the rotor to rotate relative to the stator, the control circuit being further configured to operate in a braking mode in which it continually connects at least a first and a second one of the windings to a common rail to form a closed current path to induce braking of the rotor relative to the stator, wherein the control circuit is configured to enter the braking mode in response to a trigger exogenous to the motor indicative of a fault condition.

Abstract: A motor drive circuit for driving an electric motor includes a plurality of driver circuits, each one of the plurality of driver circuit comprising a high side transistor coupled to a low side transistor in a half bridge arrangement, wherein each one of the high side transistors and each one of the low side transistors has a respective control node and respective first and second current passing nodes, wherein the second current passing node of each of the high side transistors is coupled to the first current passing node of a respective one of the low side transistors at a respective junction node, wherein each one of the plurality of driver circuits is operable to drive a respective current out of a respective junction node into a respective winding of the electric motor. The motor drive circuit further includes a capacitor coupled to the first current passing node of each one of the high side transistors, the capacitor operable to hold a capacitor voltage.

Abstract: A method of controlling an electric motor assembly includes detecting a backspin event of an electric motor, and managing a response to the detected backspin event of the electric motor. The backspin event of the electric motor is detected based at least in part on feedback from a sensor configured to measure a current or a voltage on a cable coupled to the electric motor. The response includes communicating an alert to personnel, controlling the voltage on the cable to be less than a voltage threshold, or any combination thereof.

Abstract: Disclosed are a shutdown method for motor and a motor driving circuit using the same. The method comprises: shutting down a higher gate switch and a lower gate switch when a supply voltage decreases, such that the storage capacitor is charged via a back electromotive force, wherein the back electromotive force decreases as the motor gradually stops; driving the motor when the voltage of the storage capacitor is again larger than the first threshold voltage; determining whether the voltage of the storage capacitor is lower than a shutdown threshold voltage when the voltage of the storage capacitor is lower than the first threshold voltage, wherein the shutdown threshold voltage is lower than the first threshold voltage; and turning on the lower gate switch when the voltage of the first threshold voltage is lower than the shutdown threshold voltage, wherein the back current is related to the back electromotive force.

Abstract: A remote gun charger including a charger member configured to selective couple to, and disengage from, a gun having a charger handle configured to charge the gun. The charger includes a catch configured to be positioned by the charger member to selectively position the charger handle and charge the gun. The catch has a first position configured to selectively engage the charger handle, and a second position configured to disengage from the charger handle and allow the gun to be fired.

Abstract: Apparatus for monitoring an Electrical Submersible Pump (ESP) are provided, and example of an apparatus includes a rotation rate or other sensor located in, for example, an ESP gauge. When the ESP is started the rotating elements rotate in a first direction while the static elements will experience an opposing torque in a second opposite direction. The small rotational movement of the ESP gauge housing, for example, is sensed by the sensor and is used to determine the direction of rotation of the motor and pump to ensure proper ESP motor and/or ESP assembly configuration.

Abstract: A method for controlling a controlled switch operates a power supply of an electric motor from an AC voltage source. The method includes actuating closure of the controlled switch, an instant of actuation of which is dependent on a value characteristic of a value of an electric voltage across terminals of the controlled switch. A control device for such a controlled switch includes elements for implementing the method.

Abstract: A power conversion device for driving a load, including a power conversion device main body configured to receive an input of a power supply voltage and to drive the load, and a brake circuit configured to protect the power conversion device main body from overvoltage applied thereto. The brake circuit includes a Zener diode that becomes conductive when the voltage applied to the power conversion device main body exceeds a predetermined value, to thereby suppress the voltage.

Abstract: Disclosed is a control method of an electronic parking brake system, which variably controls the duty of voltage applied to a motor upon release of the electronic parking brake system. The control method includes controlling voltage applied to a motor to a first duty ratio upon release of the electronic parking brake system, controlling the voltage applied to the motor to a second duty ratio greater than the first duty ratio if locking of the motor occurs and the motor is not operated, and controlling the voltage applied to the motor to the first duty ratio if locking of the motor is released and the motor begins to operate, after the control of voltage to the second duty ratio.

Abstract: A clutch control unit includes a clutch motor controller that controls a clutch motor. The clutch motor controller has a target clutch motor current computing unit that computes a target clutch motor current for adjusting torque of the clutch motor to be torque corresponding to an operating state of the vehicle, and a motor driving and braking selection unit that selects a motor driving mode in which the clutch motor is driven by applying feedback control on an output of the clutch motor or a motor braking mode in which the clutch motor is braked by short-circuiting the clutch motor according to a difference between the target clutch motor current and an actually detected clutch motor current. It thus becomes possible to provide a control system of a transmission that engages a clutch by a motor braking force in a manner that suits the running state of the vehicle.

Abstract: A damper system for a vehicle including an electromagnetic damper, wherein the electromagnetic damper includes: (i) an electromagnetic motor; (ii) a motion converting mechanism; and (iii) an external circuit including (A) a first connection passage, (B) a second connection passage, (C) a first-connection-passage-current adjuster, and (D) a second-connection-passage-current adjuster, wherein the damper system comprises an external-circuit controller including: (a) a main-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as a main adjuster, a first control for mainly damping the relative vibration of the sprung portion and the unsprung portion; and (b) an auxiliary-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as an auxiliary adjuster, a second control for assisti

Abstract: A damper system for a vehicle including an electromagnetic damper, wherein the electromagnetic damper includes: (i) an electromagnetic motor; (ii) a motion converting mechanism; and (iii) an external circuit including (A) a first connection passage, (B) a second connection passage, (C) a first-connection-passage-current adjuster, and (D) a second-connection-passage-current adjuster, wherein the damper system comprises an external-circuit controller including: (a) a main-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as a main adjuster, a first control for mainly damping the relative vibration of the sprung portion and the unsprung portion; and (b) an auxiliary-adjuster control portion configured to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as an auxiliary adjuster, a second control for assisti

Abstract: A fan system comprising a motor, a motor driving circuit and a control unit is disclosed. The motor driving circuit is coupled to the motor. The control unit is coupled to the motor driving circuit, generates a forward rotation command for controlling the motor to rotate in a predetermined direction when the control unit receives electrical power, and generates a backward rotation command for controlling the motor to rotate in a direction opposite to the predetermined direction when the control unit fails to receive the electrical power.

Abstract: A semiconductor integrated circuit for sensorless driving of a brushless motor, has: an induced voltage detecting circuit which includes a comparator for comparing a voltage induced in an exciting coil by a rotation of a rotor of the brushless motor with a midpoint voltage of the rotor of the brushless motor and outputting a detection signal corresponding to a comparison result, and detects a zero cross point where the induced voltage crosses the midpoint voltage; a logic circuit that outputs a control signal for controlling the brushless motor, in response to a command signal for regulating an operation of the brushless motor and an output signal of the comparator; and a power transistor circuit that supplies a driving current to the exciting coil.

Abstract: A method for testing a motor having a rotor and a winding is provided. The method includes steps of (a) providing a power to rotate the rotor to a predetermined speed, (b) removing the power, (c) measuring a terminal voltage of the winding while a current within the winding is zero, (d) obtaining a back electromotive force in the winding by compensating the terminal voltage with a performance of the rotor, (e) selecting a characteristic of the back electromotive force and (f) determining a magnetization of the motor by comparing the characteristic with a predetermined parameter.

Abstract: A method for controlling brake resistors and a brake chopper, the number of brake resistors being two or more and the brake resistors being connected in series with switches to be controlled, the series connection being connected between a positive and a negative rail of a DC voltage intermediate circuit, the method comprising the step of determining a magnitude for a voltage of the DC intermediate circuit; and determining a first voltage limit and a second voltage limit. The method further comprises the steps of switching brake resistors to the intermediate circuit in a periodically alternating manner, each switch being switched during a switching period and the on-period of each switch in a switching period being responsive to the magnitude of the voltage in the DC voltage intermediate circuit when the voltage is above the first predetermined limit and below the second predetermined limit.

Abstract: A storage drive implements a method for a BEMF voltage reduction during a deceleration period of an electric motor of the storage drive. In operation, the electric motor is disconnected from a power supply during an entirety of the deceleration period of the electric motor to prevent any flow of a BEMF current into the power supply, and the electric motor is connected to a power return during a segment or an entirety of the deceleration period of the electric motor to dissipate any BEMF voltage within the electric motor.

Abstract: There is provided a brushless motor drive control circuit capable of assuring an S/N ratio of a predetermined counter electromotive voltage and suppressing lowering of efficiency of a brushless motor at a high-speed rotation.

Abstract: In the motor stop control device according to the embodiment, a main CPU is provided which executes any one of reel stop control process 1 and the reel stop control process 2 when the stop instruction of a stepping motor occurs. In the reel stop control process 1, the main CPU changes a drive power source A, which is applied to the stepping motor rotating at the constant speed, to the drive power source B2, the voltage value of which is lower that that of the drive power source A, and executes the stop control of the stepping motor by the 2-phase excitation. In the reel stop control process 2, the main CPU changes the drive power source A, which is applied to the stepping motor rotating at the constant speed, to the drive power source B1,the voltage value of which is between the voltage values of the drive power source A and the drive power source B2, and executes the stop control of the stepping motor by the 2-phase excitation.

Abstract: A motor controller comprising, a detector configured to perform a difference processing for information relating to a counter electromotive force and an induced electromotive force generated by a stepping motor, and to generate a driving control signal based on a result of the difference processing, and a driver configured to drive the stepping motor based on the driving control signal.

Abstract: A rotation information detection device detects rotation information of a DC motor based on a surge component waveform superimposed on a voltage waveform between the terminals of the DC motor or a current waveform of the DC motor, a circuit is provided which supplies a current of a current value Ipwm 45% during motor forward rotation or Ipwm 55% during reverse motor rotation to the motor over the period from when the motor starts braking operation to when it stops.

Abstract: The reference signal generation unit 110a integrates, in the integration circuit 3, a staircase signal generated by the staircase generation unit 2, and thereby generates a reference signal VCTA whose signal level changes continuously over time, and which represents a limit value for the supply current. According to the control of the PWM control unit 120a, the bridge rectification circuit 130a maintains the coil supply current at the limit value, using a current chopper method. Additionally, when the current supply is stopped, the bridge rectification circuit 130a performs synchronous rectification, where the transistors 10 and 12 are brought into conduction, and a regenerative current is circulated in a closed circuit formed with the coil 19a. When the reference signal VCTA decreases relatively fast, the synchronous rectification prohibition unit 115a prohibits one of the transistors 10 and 12 from being brought into conduction when the current supply is stopped.

Abstract: A patient support including a propulsion device for moving the patient support. An automatic braking system is provided to selectively brake the patient support.

Abstract: A three-wire reversing system for a permanent magnet, reversible, brush-type, direct current (DC) motor has a three-wire alternating current (AC) input voltage source which supplies electrical current to at least one capacitive element. This capacitive element and the DC motor replace a permanent split capacitor (PSC) and an AC motor in a prior art three-wire reversing system.

Abstract: An electrical machine comprises a rotor without windings, a stator having an armature winding 24, 25 and a field winding 10 for generating a magnetomotive force in a direction extending transversely of the magnetomotive force generated by the armature winding. An electronic circuit 40 is provided for controlling the current in the armature winding 24, 25 such that periods in which a magnetomotive force in one direction is associated with a first current pulse alternate with periods in which a magnetomotive force in the opposite direction is associated with a second current pulse. A position sensor is provided for monitoring the rotational position of the rotor and for supplying output signals at a rate dependent on the speed of rotation of the rotor. Furthermore a control system supplies control signals to the circuit 40 to control the current in the armature winding 24, 25 in response to the output signals.

Abstract: A vehicle drive assembly includes an electric motor directly coupled to a rotatable member for driving a wheel, for example, without gear reduction assemblies between the motor output and the driven wheels. A multi-phase, high pulse current stepper motor is used as the motor in one example. A driven wheel is supported by a wheel mounting member in a conventional fashion. A rotatable member associated with the wheel mounting member is directly coupled to an output of the stepper motor. The stepper motor can selectively operate in several modes. A first mode provides driving torque to the vehicle wheels, a second mode provides a braking force and an optional third mode allows the stepper motor to serve as a parking brake.

Abstract: A capacitor powered electronic emergency device retracts and parks an actuator into a resistive parking position with a crash stop barrier. Due to variations of the kinetic status of the actuator at the begin of the retraction, the actuator reaches the resistive parking position with different velocities, which can be at a level that causes the actuator to bounce off the crash stop barrier. A modulating pulsing of the energy flow extends the discharge time of the capacitor long enough to provide sufficient energy to compensate an eventual bounce-off. The use of transistors in the device keeps the internal energy consumption low. An increase of the pulsing frequency in dependence on the capacitor voltage results in a high average current flow.

Abstract: A holding brake control circuit is provided for use in conjunction with a servo-motor having an electrically operated holding brake. The holding brake has a pair of electric brake terminals and the brake is retained in a released condition as long as at least a preset brake voltage is maintained to the brake terminals. The holding brake control circuit includes a pair of output terminals connected to the electric brake terminals as well as a pair of power input terminals electrically connected to an electric power source. The electric power source, furthermore, has a higher voltage than the preset brake voltage. At least one capacitor is electrically connected in parallel with the input terminals so that the capacitor charges when power is applied to the input terminals. A voltage regulator has power inputs connected in parallel with the capacitor and a regulated voltage output connected in parallel with the output terminals for the control circuit.

Abstract: A method and circuit for controlling a voice coil motor (VCM) for a disk drive actuator assembly such that the actuator assembly moves to a landing area at a constant velocity when the disk drive loses power. The circuit includes a sense amplifier for sensing and amplifying current to the VCM, a current integrator for determining the actual velocity of the actuator assembly during every seek, an H-bridge driver, which controls the direction of current to the VCM and magnitude of voltage across the VCM and a window compare and logic block that receives and sorts information from the integrator, and a timer. The window compare and logic block determines the direction of current and magnitude of voltage to apply to the VCM. During a loss of power, e.g.

Abstract: A method and a device for electrical braking of an all-mains motor by which disconnection of supplied feed current to the motor causes an electric switching operation, whereby electric current arranged to cause a reversed rotary direction for the rotor (1) of the motor is supplie. According to the invention, supplied braking power (P) is controlled and reduced on basis of the successive reduction of rotary speed for the motor until the rotor (1) of the motor has substantially completely ceased to rotate, preferably substantially corresponding to an inverted "soft start" for the motor, whereafter supplied braking current feed is interrupted. It is advantageously monitored whether or not normal start of the motor has been performed, electric switching to braking only being made possible provided that such a start sequence has been indicated.

Abstract: A voltage vector overmodulation technique considering a counter electromotive force of a motor with respect to a voltage applied to the motor in a transient state during the operation of the motor, selects a voltage having the least logarithmic difference between a counter electromotive force according to the voltage applied to the motor and a command voltage as an application control voltage of the motor. Thus, since a response voltage to correspond to a transient state during the operation of the motor is selected considering the dynamic characteristic of the motor, a voltage most appropriate for the operation of the motor can be selected. Also, the current controller and the speed controller of the motor can stably be operated and maximum use of the available torque of the motor is possible.

Abstract: The present invention provides efficient dynamic braking of a DC motor to complement servo loop control. This invention uses a combined technique where, first, a reversed-torque signal is applied to a standard motor controller that then reverses armature current to initiate braking and, second, a dissipative load is switched between the DC voltage bus and ground in order to dissipate the regenerated current as the motor slows. As braking action continues, the dissipative load is repeatedly switched into and out of the circuit, whenever voltage on the DC voltage bus, caused by regenerated current, exceeds a selected threshold. Hysteresis is provided to maintain current flow for a controlled period, providing a pulse-width modulation of the switching action. The invention allows controlled, fast braking for repeated operations and improves overall servo positional control in high-inertia applications, such as for an image processing apparatus using an imaging drum.

Abstract: A power down brake latch circuit for dynamically braking a spindle motor in a disk drive system is disclosed. The power down brake latch circuit includes a reservoir capacitor, a smoothing capacitor, a timing circuit, and a logic circuit. The timing circuit includes a voltage divider and a bandgap comparator. The smoothing capacitor absorbs a BEMF voltage from the spindle motor as it rotates after losing power. The timing circuit generates a first signal when a voltage on the smoothing capacitor falls below a threshold. The logic circuit brakes the spindle motor in response to the loss of power and the generation of the first signal.

Abstract: The wheel brakes of each vehicle axle or side or diagonal are supplied with current by a separate voltage source. To reduce the load on the vehicle's electrical system, the wheel brakes of a front axle are supplied with current first, and then the wheel brakes of a rear axle are supplied with current.

Abstract: A control system for a hybrid vehicle ensures the best possible utilization of onboard energy resources for different operating conditions of the vehicle. The control system utilizes a strategy modified in real time depending on the input from sensors measuring vehicle speed, the current and voltage levels at different locations in the system. The vehicle has an auxiliary power unit, at least one energy storage device and at least one electric drive motor for traction. The vehicle has a high load driving condition, a low load driving condition and a regenerative braking condition. A voltage control sets system voltage to a charging voltage in the low load condition and regenerative braking condition, and sets system voltage to an output voltage from the energy storage device for the high load condition.

Abstract: A system for driving a hard disk drive spindle motor is disclosed. The system comprises a spindle motor control circuit (120) and a spindle motor power circuit (220). The system also includes at least one disk (22) attached to a rotatable spindle (21) and a spindle motor (400) which receives power signals from the spindle motor power circuit (220) and controls the rotation of the spindle (21). The spindle motor control circuit (120) comprises a multiplexor (127) which transmits either a pulse width modulation signal or a current control signal in response to a mode selection signal, and a spindle predriver (125) which receives the multiplexor output signal and transmits spindle motor control signals to the spindle motor power circuit (220).

Abstract: The present invention provides for electronic braking of DC brushless motors by developing a feedback signal based on the back EMF of the motor. This feedback signal is used to provide a signal to the motor permitting current flow from the motor into the controller of a controlled level to slow the motor down. Reliance on the back EMF of the motor eliminates the need for a commutation signal when an emergency stop is required.

Abstract: A CMOS disk drive motor control circuit which has back-EMF regulator circuitry which prevents the back-EMF from the disk drive motor from exceeding a predetermined level. The back-EMF provides an alternate power source for parking the read/write head when power is removed from the disk drive. The circuit is fabricated as a single CMOS integrated circuit which is coupled between a power supply and the disk drive motor. The disk drive control circuit also includes a blocking diode through which power from the power supply flows to the motor and which prevents dissipation of a back-EMF from the motor when power is removed from the motor, and disk drive head parking circuitry which uses the back-EMF to retract and park the disk drive head.

Abstract: A motor drive particularly suited for decelerating an AC motor includes a signal converting circuit, a monitoring circuit and a control circuit. The signal converting circuit is coupled to a source of DC power via a DC bus and a capacitive circuit is coupled across the DC bus to store energy produced by the motor during deceleration of a primarily inertial load. The signal converting circuit produces and applies drive signals to the motor based on control signals from the control circuit. The control circuit produces control signals for generating an output waveform duty cycle for the drive signals suitable for maintaining a predetermined voltage-to-frequency relationship. The frequency of the output signals is selectable to control the output speed of the motor. During deceleration, the monitoring circuit detects rises in the DC bus voltage, indicating that the motor is tending to slow at a rate less than the desired deceleration rate.

Abstract: The invention relates to a method for braking an alternating-current motor when the alternating-current motor (1) is supplied by a frequency converter (4) comprising an intermediate circuit (2). In accordance with the invention, when the voltage (uc) of the intermediate circuit (4) reaches a predetermined value during braking, the magnetization of the motor (1) is increased to increase the thermal losses of the motor, and, once the voltage (uc) of the intermediate circuit drops below said predetermined value, the increased magnetization is removed.

Abstract: An inductive load drive circuit for driving an inductive load, such as a motor, and for preventing charging of a power source by the back electromotive force of an inductive load. The inductive load drive circuit uses a battery as the power source for supplying power to the load. A first switching mechanism can serially connect and disconnect the inductive load and the battery. The first switching mechanism is controlled so that it disconnects the inductive load from the battery when the inductive load is in a condition in which the inductive load is able to generate back electromotive force or when the inductive load will be shifted to such a condition. Moreover, a bypass circuit can be used to consume the energy of the back electromotive force of the inductive load. A second switching mechanism is serially connected to the bypass circuit, with the serial combination of the second switching mechanism and the bypass circuit being in parallel with the power source.

Abstract: In a disk drive, the read-write heads of the disk drive should be parked during a power failure. The kinetic energy of the spinning rotor is used to move the head away from the disk's surface. A high voltage is produce from the low voltage spindle motor by using a BEMF voltage to step up the voltage in a voltage supply capacitor to a higher voltage by enabling or disabling a switch connected to a comparator. When the switch is turned on, it shorts the rectified voltage in the stator windings to ground in order provide a current path for a current formed in the coils by the BEMF. When the current reaches a predetermined level, the switch is turned off. The current flows through the voltage supply capacitor so that its voltage is "kicked-up" by the inductance of the windings and by the BEMF still present in the stator windings. This increased voltage is used to park the heads and to brake the motion of the spindle. Two control feedback loops are used to more efficiently enable the voltage conversion.

Abstract: Method and apparatus for retracting an actuator comprising determining back emf voltage generated by the actuator motor; applying the determined voltage to a capacitor-resistor network; applying a holding voltage to the capacitor-resistor network. The application of the determined voltage and the holding voltage together charges a capacitor in the capacitor-resistor network to develop a charged capacitor voltage. The method and apparatus further comprises terminating application of the determined voltage to the capacitor-resistor network upon charging of the capacitor, and discharging the capacitor through the capacitor-resistor network to provide a forcing voltage to the actuator for retract operation. The forcing voltage initially forces a high deceleration current in the actuator. Further, the forcing voltage decays with time to a predetermined holding voltage to complete the retract operation.

Abstract: A circuit arrangement for the triggering of motors includes a winding arrangement, the connections of which can be connected to electricity sources by means of a commutation facility. Several or several groups of electricity sources can be connected to the same connections at the same time to make rapid processes of acceleration and deceleration of the rotor of the motor possible. A rotary field causing deceleration can thereby be superimposed upon a rotary field causing acceleration without the necessity of interrupting a control loop for the electricity source generating the rotary field causing acceleration.

Abstract: A process is provided for compensating for offset in the actuator current of the servo system of a disc drive. A typical disc drive includes a power amplifier providing actuator current to the actuator coil of the drive. A sensing resistor is responsive to the actuator current to provide a feedback signal representative of the magnitude of the actuator current, the feedback signal being provided to the power mechanism to derive the actual actuator current. By the present technique, offset in the actuator current is compensated by operating the transducer to move at predetermined constant velocities (for example, the maximum velocities) in first and second opposite directions across the surface of the disc and by measuring the resulting actual velocities. The feedback signal is adjusted based upon any difference between the actual velocities measured in the first and second directions.