Abstract: A method for setting a lead-angle value of a motor drive control circuit is disclosed. The motor drive control circuit energizes and drives the windings of a motor with an energizing timing based on a stored lead-angle value. The method includes the steps of: rotating a rotor at a given rpm (step S102), energizing and driving the windings during the rotation at the given rpm with the lead-angle value being switched (step S110); calculating an average value of current amount that energizes and drives the windings (step S114); calculating a total value of consecutive multiple average values for each lead-angle value (step S120); finding a smallest total value among the total values, and setting a lead-angle value corresponding to the smallest total value as a stored lead-angle value (step S122).

Abstract: A condition of an engine is diagnosed based on information provided by signals from speed sensors associated with the engine or other signals associated with a generator operationally connected to the engine. Different types of degradation are distinguished based on discerning characteristics within the information. Thus, a degraded engine component can be identified in a manner that reduces service induced delay.

Abstract: Diagnosing auxiliary equipment associated with an engine. A condition of the auxiliary equipment is diagnosed based on information provided by signals from a generator operationally connected to the auxiliary equipment or other signals associated with the engine. Different types of degradation are distinguished based on discerning characteristics within the information. Thus, a degraded auxiliary equipment component can be identified in a manner that reduces service induced delay.

Abstract: An electronic device and a method for controlling fan speed of the electronic device include setting a speed range corresponding to a variety of pulse-width modulation (PWM) duty cycles of the fan, and setting a speed variation value of the fan. The method further includes reading the PWM duty cycle and detecting an actual speed of the fan, and adjusting the PWM duty cycle in the PWM duty cycle instruction according to the speed variation value.

Abstract: Motors, such as DC motors, and methods and systems for operating a motor, are described. The motor is optionally an electronically commutated motor. The motor comprises one or more electromagnets and a controller device to control the electromagnets. The controller device is configured to calibrate the motor operation in a desired installation to determine the torque needed to achieve a desired operating speed by causing the motor to ramp up to the desired speed, measuring an electric current needed to operate the motor at the desired speed, and setting a value corresponding to a first speed tap using the measured electric current. The controller device is configured to operate the motor in a substantially constant torque mode using the set value at least after the completion of the calibration operation. The motor may be configured for use in a ventilation system, such as an HVACR system.

Abstract: Various embodiments of an electric motor and electronic control for an electric motor are disclosed. An exemplary electric motor comprises a single-phase brushless permanent magnet electric motor. In exemplary embodiments, the electronic motor control is configured to commutate an electric motor at a frequency other than line frequency, perform pulse width modulation, and drive the electric motor with a drive waveform that approximates the counter-electromotive force of the motor.

Abstract: A control circuit controls an electric motor and includes: a measuring device configured to measure a first phase current of the motor and provide a corresponding first analog signal; an analog-to-digital converter structured to convert the first analog signal into a first digital signal; a conversion module for generating a first converted digital signal representative of the first digital signal expressed in a rotating reference system; a node structured to compare the first converted digital signal into a first reference signal and generate a first error signal; and a measure control circuit structured to provide a timing signal of the analog-to-digital converter depending on the first error signal and a time delay introduced by the measuring device.

Abstract: In a method and a device for pulse width modulated (PWM-) activation of an electrical drive motor (2) of an adjustment arrangement based on a reference of the mechanical system of the adjustment arrangement that corresponds to a relationship between the force (F) on the drive motor (2) and the adjustment path (s) or the adjustment time (t) of the adjustment arrangement stored in a memory (9), an anticipated future force value (F(t+t0)) is determined based on the reference of the mechanical system in order to adjust the PWM activation in advance by utilizing this future force value such that motor synchronization fluctuations can be prevented upon anticipated mechanical fluctuations in the adjustment arrangement.

Abstract: A stepper motor driver system includes: a digital signal controller configured to digitally synthesize synthesized analog voltage signals that will induce a desired velocity of a stepper motor when applied to a pair of stepper motor windings; and voltage amplifiers, communicatively coupled to the digital signal controller, configured to amplify the synthesized analog voltage signals to produce amplified analog voltage signals and to output the amplified analog voltage signals; where the digital signal controller is configured to synthesize the analog voltage signals by affecting at least one of a phase or an amplitude of each of the analog voltage signals as a function of the desired velocity of the stepper motor.

Abstract: A heating, ventilation and air conditioning (HVAC) system is provided. The system includes an integrated motor including a plurality of operating speeds and an input for selecting one of the plurality of operating speeds. The system further includes a system controller and an adjustment module. The adjustment module includes a plurality of operating modes each associated with one of the plurality of operating speeds and the ability to manually vary associations between the plurality of operating modes and the plurality of operating speeds. The adjustment module selects one of the plurality of operating modes on the basis of control commands received from the system controller and setting programmed or manually entered into and stored in the adjustment module and controls the integrated motor according to the operating speed associated with the selected operating mode.

Abstract: A motor magnetic pole position correction method includes preventing a movement of a movable element of a direct drive motor by mechanical brake (step S9), generating a command that designates a position spaced or separated from the present position (step S10), detecting a torque command value of the direct drive motor (step S12), determining a magnetic pole position correction value based on a comparison between the detected torque command value and a predetermined threshold value (steps S14 and S16), storing the determined magnetic pole position correction value in a memory (step S18), and performing motor control using an electrical angle offset value obtained based on the magnetic pole position correction value stored in the memory.

Abstract: If magnitude relations between the output terminal voltage based on a DC negative terminal of the inverter and a threshold voltage that is a fixed value are compared, polarity thereof is changed at a predetermined rotor phase. The magnitude relation, for example, is detected by an inexpensive and simple apparatus such as a level shift circuit and a NOT circuit. The rotor phase of the permanent magnet synchronous motor is inferred on the basis of changes in the magnitude relation and if it is differentiated, a rotation speed is inferred. If the inferred values of the rotor phase and rotation speed are fed back to synchronous operation or vector control, the free-running permanent magnet synchronous motor is restarted.

Abstract: A circuit configuration for driving an electric motor includes a signal evaluation module, which stores a number of output patterns. An input pattern is specified, and as a function of the input pattern, one of the output patterns is output, by which the electric motor is driven.

Abstract: A method for automated startup and/or for automated operation of controllers of an electrical drive system with vibrational mechanics with the following steps: (a) determining a preliminary value of at least one parameter; (b) determining a model of the electrical drive system by determination of initially a non-parameterized model through the recording of frequency data during operation of the drive system subject to the utilization of the preliminary value of at least one parameter and the subsequent determination of parameters of the electrical drive system based on the frequency data and subject to optimization of at least one preliminary value of at least one parameter by a numerical optimization method on the basis of the Levenberg-Marquardt algorithm and (c) parameterizing at least one controller of the electrical drive system by at least one of the determined parameters.

Abstract: A circuit for alarming abnormal state of a computer fan includes a detection circuit coupled to the computer fan, a controller coupled to the detection circuit and the computer fan, an alarm unit coupled to the controller. The detection circuit detects a power source and a speed control signal received by the computer fan, the controller determines the work state of the computer fan according to the power source, the speed control signal, and a speed signal received from the computer fan and raises an alarm through the alarm unit if the computer fan is not working normally.

Abstract: A method of controlling an electric machine that includes sequentially exciting and freewheeling a winding of the electric machine. The winding is excited in advance of zero-crossings of back emf in the winding by an advance angle, and the winding is freewheeled over a freewheel angle. The method then includes varying the advance angle and the freewheel angle in response to changes in the voltage used to excite the winding. Additionally, a control system for an electric machine, and a product incorporating the control system and electric machine.

Abstract: An angle calculator determines an angle of a rotor. An angular speed calculator determines an angular speed of the rotor. A command current calculator determines a command current defined on a dq-axis. An open loop controller determines a command voltage defined on the dq-axis in accordance with a circuit equation of a motor, based on the command current and the angular speed. A dq-axis/three-phase converter converts the command voltage into a three-phase command voltage. A resistance calculator and a ?-value calculator respectively determines circuit resistance including armature winding resistance and a number of armature winding linkages which are included in the circuit equation of the motor, based on temperature of the motor detected by a temperature sensor and with reference to a table or the like which is stored in advance.

Abstract: In order to automatically detect a mechanically commutated DC motor, it is provided to acquire an electrical engine size, to determine current ripples in the engine size, to evaluate the amplitude, the duration and/or time position of the detected current ripples and to compare to known ripple patterns, and to choose from a known key data table a number of key data assigned to a certain engine type, when the amplitude, during and/or time position of the detected current ripples correspond to a ripple pattern, which is assigned to the engine type.

Abstract: A motor control apparatus includes a sensing module, a phase modulating module, a duty cycle modulating module and a driving module. The sensing module detects a motor to generate a sensing signal. The phase modulating module receives the sensing signal and generates a phase modulation signal in accordance with the sensing signal. The duty cycle modulating module receives the phase modulation signal and generates a duty cycle modulation signal in accordance with the phase modulation signal. The driving module receives the duty cycle modulation signal and generates a motor control signal for controlling the motor in accordance with the duty cycle modulation signal.

Abstract: A method for detecting a regulating variable of a mechanically commutated DC motor in a positioning device for a motor vehicle is provided. The DC motor has a standard ripple pattern, which contains per engine cycle or semi-cycle at least one index ripple, which is classified with regard to amplitude, duration and/or time position. The counter-electromotoric power is calculated from a measured motor current and the measured motor voltage by a motor model. An alternating element corresponding to the current ripples is extracted from the counter-electromotoric power, which in turn is used to determine the current ripples. Further, in at least one engine cycle or engine semi-cycle the index ripple is identified and the total identified current ripples are counted. The result of the count is hereby corrected when the index ripple is not counted at the expected position.

Abstract: A system includes a power control module, a period determination module, and a control module. The power control module controls current through stator coils of a motor to rotate a rotor. The period determination module determines a first length of time between a first set of induced stator coil voltages and determines a second length of time between a second set of induced stator coil voltages. The control module determines whether an external disturbance disturbs rotation of the rotor based on a difference between the first and second lengths of time.

Abstract: Method for control of synchronous electrical motors with application for stepper and Brush-Less Direct Current motors for which there is an explicit relation between the active electrical power supplied to the motor and the mechanical power that the motor delivers to the load. The active electrical power Pel consumed by the motor is measured and according to FIG. 3 the mechanical power Pmech and the maximum available mechanical power Pmech max are determined. The ratio between Pmech and Pmech max is calculated and is compared to the set value of the same ratio. If it is greater than the set one either the operating currents are increased either the operating speed is decreased or both operations are executed. But if it is smaller—either the operating currents are decreased either the operating speed is increased or both operations are executed.

Abstract: A motor starting apparatus includes a driving signal generating unit that generates an open-loop driving signal and a drive circuit that is connected to a motor. The driving signal generating unit includes a data storing unit that stores therein predetermined data, a velocity integrating unit that integrates velocity data, a phase adjusting signal generating unit that generates a phase adjusting signal, a three-phase driving signal generating unit that generates a three-phase applied voltage, and a drive circuit driving unit that generates a driving signal of the motor. The three-phase driving signal generating unit performs open-loop driving by outputting the three-phase applied voltage based on the phase adjusting signal to the drive circuit driving unit.

Abstract: One embodiment of the method includes setting up a testing architecture where the testing architecture includes a test IPM machine having an output shaft coupled to an output shaft of a secondary speed control machine. The method further includes controlling the secondary speed control machine to drive the output shaft of the test IPM machine at a first desired speed, determining a pair of desired direct and quadrature axis currents for each of a plurality of peak current magnitudes, and recording characterization data associated with each pair of desired direct and quadrature axis currents. The controlling, determining and recording steps for each of a second through nth desired speeds may be repeated. Control lookup tables for operation of an IPM machine may be generated from the characterization data.

Abstract: A motor magnetic pole position correction method includes preventing a movement of a movable element of a direct drive motor by mechanical brake (step S9), generating a command that designates a position spaced or separated from the present position (step S10), detecting a torque command value of the direct drive motor (step S12), determining a magnetic pole position correction value based on a comparison between the detected torque command value and a predetermined threshold value (steps S14 and S16), storing the determined magnetic pole position correction value in a memory (step S18), and performing motor control using an electrical angle offset value obtained based on the magnetic pole position correction value stored in the memory.

Abstract: Method for control of synchronous electrical motors with application for stepper and Brush-Less Direct Current motors for which there is an explicit relation between the active electrical power supplied to the motor and the mechanical power that the motor delivers to the load. The active electrical power Pel consumed by the motor is measured and according to FIG. 3 the mechanical power Pmech and the maximum available mechanical power Pmech max are determined. The ratio between Pmech and Pmech max is calculated and is compared to the set value of the same ratio. If it is greater than the set one either the operating currents are increased either the operating speed is decreased or both operations are executed. But if it is smaller—either the operating currents are decreased either the operating speed is increased or both operations are executed.

Abstract: An apparatus, system, and method are disclosed for controlling fan speed in a power supply. The apparatus measures input power to the power supply and measures the output power provided by the power supply over an interval. The apparatus determines values for the input power and output power and, using the two, determines how much power has been dissipated in the power supply. Power dissipation values are associated with particular fan speeds, and the apparatus adjusts the speed of the fan in the power supply based on how much power was dissipated during the interval. Increasing levels of power dissipation increases the fan speed, and decreasing levels of power dissipation decrease the fan speed.

Abstract: The invention relates to an electronically commutated electric motor. The electric motor comprises a stator, and a rotor, in particular a permanent-magnetic rotor. The electric motor further comprises a control unit connected to the stator. The control unit is designed to actuate the stator such that the stator can generate a magnetic rotating field for rotationally moving the rotor. According to the invention, the control unit of the electric motor is provided with a power output stage having semiconductor switches. Subject to the low-resistance, or short-circuited, semiconductor switch of the power output stage, in particular as a result of defect, the control unit is designed to actuate the stator for generating the rotating field such that during a complete rotor revolution, the rotor can provide a mechanical output, or in the operational mode, a braking torque of the electric motor caused by the defect is reduced, or completely neutralized, by the low-resistance, or short-circuited, semiconductor switch.

Abstract: In order to automatically detect a mechanically commutated DC motor, it is provided to acquire an electrical engine size, to determine current ripples in the engine size, to evaluate the amplitude, the duration and/or time position of the detected current ripples and to compare to known ripple patterns, and to choose from a known key data table a number of key data assigned to a certain engine type, when the amplitude, during and/or time position of the detected current ripples correspond to a ripple pattern, which is assigned to the engine type.

Abstract: A motor controller for controlling a permanent magnet motor having a rotor having a permanent magnet and a stator having multiphase windings including a position detector generating and outputting rotor rotational position signal; a waveform data storage storing sinusoidal waveform data; a drive signal output section reading the waveform data from the waveform data storage at timings determined based on the rotational position signal and outputting a voltage signal corresponding to the waveform data to the windings through a drive section; a data history storage storing data corresponding to the voltage signal of previous control period; and an output data modifier that, when outputting the voltage signal in current control period, compares corresponding waveform data with previous waveform data, and if difference between the current and the previous data is equal to or greater than a predetermined value, current output data is modified by a portion of the difference.

Abstract: A method for the identification without a shaft encoder of magnetomechanical characteristic quantities, in particular the mass moment of inertia J and the permanent magnetic flux ?PM between rotor and stator of a three-phase synchronous motor, comprising: —constant voltage supply U1d in the d flux axial direction; —test signal voltage supply U1q in the q transverse flux axial direction; —measuring signal current measuring I1q of the q transverse flux axial direction; —identification of magnetomechanical characteristic quantities of the synchronous motor on the basis of the test signal voltage U1q and of the measuring signal current I1q; whereby the rotor can execute deflection movements with pre-definable maximal amplitudes. Method use also for control of electrical drives.

Abstract: An electric machine is disclosed comprising a first energy source, a second energy source, and a stator which comprises a first set of windings and a second set of windings. The electric machine has a rotor and a controller, the controller configured to control the first energy source to supply a first current to the first set of windings and control the second energy source to supply a second current to the second set of windings. The controller also detects an angular position of the rotor, detects the first current, detects the second current, and determines an optimum phase shift angle of the first current based on the angular position of the rotor, the first current, and the second current. The controller controls the first energy source based on the optimum phase shift angle to modify the first current supplied to the first set of windings.

Abstract: Systems and methods are provided for pulse-width modulated control of power inverter using phase-shifted carrier signals. An electrical system comprises an energy source and a motor. The motor has a first set of windings and a second set of windings, which are electrically isolated from each other. An inverter module is coupled between the energy source and the motor and comprises a first set of phase legs coupled to the first set of windings and a second set of phase legs coupled to the second set of windings. A controller is coupled to the inverter module and is configured to achieve a desired power flow between the energy source and the motor by modulating the first set of phase legs using a first carrier signal and modulating the second set of phase legs using a second carrier signal. The second carrier signal is phase-shifted relative to the first carrier signal.

Abstract: Embodiments of the invention provide an electric machine module including a module housing. In some embodiments, the module housing can at least partially define a machine cavity into which an electric machine can be positioned. The electric machine can include a rotor assembly comprising a plurality of laminations and a least one magnet positioned substantially within the rotor assembly. In some embodiments, at least one temperature sensor can be operatively coupled to, and in thermal communication with, a portion of the rotor assembly. The temperature sensor can be configured to sense a temperature of the rotor assembly. In some embodiments, at least one transmitter can be in communication with the temperature sensor and can transmit a signal from the temperature sensor to a receiver. In some embodiments, the receiver can be coupled to the module housing and in communication with a controller.

Abstract: A disk drive is disclosed comprising a disk, a head actuated over the disk, and a spindle motor for rotating the disk, wherein the spindle motor comprises a plurality of windings. During a spin-up operation of the disk, a sinusoidal driving signal is applied to each winding of the spindle motor for a spin-up interval, wherein during at least eighty percent of the spin-up interval the sinusoidal driving signals are applied to the windings of the spindle motor open loop.

Abstract: A controller controls switching of IGBT devices of an inverter according to the desired output of the permanent magnet motor. The controller includes: a magnet temperature detection device that detects the magnet temperature of the permanent magnet motor based on the output of a temperature sensor; a setting device that sets a threshold value of the magnet temperature corresponding to the desired output of the permanent magnet motor, based on a predetermined relation between the output from the permanent magnet motor and a critical temperature, up to which demagnetization in the permanent magnet motor is not caused; and a carrier frequency control device that, when the magnet temperature detected by the magnet temperature detection device exceeds the threshold value, changes the carrier frequency, at which the IGBT devices are switched, such that a ripple current superimposed on a motor current that flows through the permanent magnet motor is reduced.

Abstract: An improved power tool system includes a power tool and an external power supply connected via a cable to provide utility and safety in a hazardous operation such as loading ammunition into a weapon in an environment of flammable materials and extreme environmental exposure. The power tool includes a sparkless motor, a sparkless controller and sparkless switches, in a sealed enclosure with improved heat transfer means. The power tool has improved torque controlling means to mitigate reaction torque to the operator and equipment when starting or stopping highly inertial loads. A sealed enclosure is provided to prevent liquids from entering the motor and controller cavity and includes a thermally conductive path to conduct heat from the motor and controller through the enclosure to cooling fins and a coolant path formed between the fins and an entrapment wall.

Abstract: This invention relates to a method of speed control selection for an electronically commutated motor comprising the following steps: (a) a motor controller receives an input signal T from a speed control selection circuit; (b) the motor controller retrieves a corresponding value for a motor running speed S from a comparison list correlating the input signal with the motor running speed, which list has been stored in the motor controller in advance, by searching the comparison list for the input signal T; and (c) the motor controller controlling a motor M to run at the motor running speed S, achieving the purpose of the speed selection. This method allows for from 2 to 256 speed choices with a single signal wire only. Such a circuit structure has the advantages of high integration, simple wiring, low cost, good performances, low failure rate, higher number of optional speeds, and simpler and more practical control.

Abstract: A control and motor arrangement in accordance with the present invention includes a motor configured to generate a locomotive force for propelling the model train. The control and motor arrangement further includes a command control interface configured to receive commands from a command control unit wherein the commands correspond to a desired speed. The control and motor arrangement still further includes a plurality of detectors configured to detect speed information of the motor, and a process control arrangement configured to receive the speed information from the sensors. The process control arrangement is further configured and arranged to generate a plurality of motor control signals based on the speed information for controlling the speed of said motor. The control and motor arrangement yet still further includes a motor control arrangement configured to cause power to be applied to the motor at different times in response to the motor control signals.

Abstract: To provide a motor driving circuit and a motor driving system wherein the circuit occupation area is small and the IC size can be reduced. A polarity inversion data generating circuit is provided to use the higher-order bits of an address counter, which do not contribute to the access to a memory, as they are, as polarity inversion instruction data (flag bit). Then, two cyclic memory accesses are performed in the same direction to read a half period of waveform data twice. A polarity inversion instruction is issued for one of the waveform data as read twice. A calculation of the polarity inversion is performed in accordance with the polarity inversion instruction, whereby waveform data corresponding to one period of sinusoidal wave can be simply generated.

Abstract: The method and a related device are for driving a brushless motor, according to which by acting solely on the control value, that is by reducing or increasing it, the driving mode eventually passes from a sinusoidal three-phase driving mode to a distorted square-wave three-phase driving mode for increasing or maximizing the voltage that may be supplied to each motor winding or vice versa. An effective drive voltage profile includes, cyclically, during each 60 electrical degree interval, profiles of re-constructed outphased complete drive waveforms including a first one stably in a saturated region, a second one exiting, at the beginning of the interval, a state of incipient saturation, and a third one reaching, at the end of the interval, a state of incipient saturation. In this way, by modifying the numerical control value it is possible to pass from a sinusoidal drive mode to a distorted drive mode of enhanced maximum peak value or vice versa.

Abstract: A method of controlling an electric machine, the method comprising storing a plurality of power maps, each power map comprising control values for driving the electric machine at different power, and selecting a power map in response to an input signal. Additionally, a control system for an electric machine, and a product incorporating the control system and electric machine.

Abstract: A current sensor of a motor controller detects the current applied to a motor drive circuit and thus a phase where a failure cannot be detected would occur without taking any measures. However, an abnormal current monitor section contained in a microcomputer receives a voltage signal of an average value of the currents detected in the current sensor by allowing a signal to pass through a first LPF having a cutoff frequency sufficiently lower than the frequency of a PWM signal. Therefore, whether or not the value is within a predetermined normal range is checked, whereby whether or not some failure containing a failure of the current sensor occurs can be easily determined about every phase.

Abstract: A control method for a motor that rotates based on flux linkages to a winding member of the motor when the winding member is energized by a drive current is provided. The method includes storing magnetic-state information indicative of a relationship between each of a plurality of predetermined operating points of the drive current and a magnetic-state parameter associated with the flux linkages. The method includes obtaining at least one of command information associated with an operating state of the motor and detection information associated with the operating state of the motor. The method includes referencing the magnetic-state information with the use of the obtained at least one of the command information and detection information to obtain a value of the magnetic-state parameter based on a result of the reference. The method includes controlling an output of the motor based on the obtained value of the magnetic-state parameter.

Abstract: Methods and systems are provided for reducing torque ripple in an electric motor. A method comprises receiving a torque command and determining a cancellation current command based on the torque command. The method further comprises generating a harmonic cancellation command based on the cancellation current command, wherein the harmonic cancellation command compensates for a phase shift and an attenuation introduced by a current regulated control module coupled to an inverter coupled to the electric motor. The method further comprises providing the harmonic cancellation command to the current regulated control module, wherein the current regulated control module is configured to control the inverter in response to the harmonic cancellation command and the torque command.

Abstract: An electrical machine, such as a switched reluctance motor, has a rotor and at least one electrically energizable phase winding. A control map is derived during production that includes a predetermined advance angle profile representing the energization of the phase winding with respect to the angular position of the rotor over a range of rotor speeds. This is stored in memory in a controller together with an angle correction factor to be applied to a predetermined portion of the advance angle profile. The angle correction factor compensates for the difference between a desired input power and the measured input power. The correction factor may be transmitted to the controller by means of radio frequency signals.

Abstract: A fan system includes a driving device, a speed detecting device and a logic device. The driving device generates a speed detecting signal and a predetermined alarm signal. The speed detecting device, which is electrically connected with the driving device, receives the speed detecting signal, and generates a low speed signal when the speed detecting signal is lower than a reference signal. The logic device is respectively electrically connected with the driving device and the speed detecting device, and generates an alarm signal when the logic device receives the predetermined alarm signal or the low speed signal.

Abstract: A system and method for controlling any of a variety of permanent magnet motors includes normalizing motor parameters with respect to demagnetization current of a motor and developing a torque-per-current relationship using the normalized motor parameters at approximately maximum torque. Using the developed torque-per-current relationship, it is possible to control any of a variety of permanent magnet motors without the need for extensive configuration of a motor control unit for a specific motor.

Abstract: A method and apparatus for controlling a rotation of a motor in a disk drive. The method includes: performing spin-up when the disk drive is operating and determining whether a disk rotation speed is less than predetermined target constant revolutions per minute (RPM); rotating a disk at predetermined low RPM when determining that the disk drive is at a low temperature and changing a rotation mode to a low-speed rotation mode if it is determined that the disk rotation speed is less than the predetermined target constant RPM; and spinning up the disk to the target constant RPM when determining that the temperature of the disk drive has increased and changing the rotation mode to a high-speed rotation mode if a disk rotation driving current decreases below a predetermined reference current value while the disk is rotating at the low RPM.

Abstract: A method and structure receives a desired rotational speed and/or step frequency for an electric motor. If the desired rotational speed is above a predetermined limit, the method performs closed-loop mode control of coil current of the electric motor by varying the average voltage supplied to the electric stepper motor according to observed feedback current from the current feedback loop connected to the electric stepper motor. To the contrary, if the desired rotational speed is not above the predetermined limit, the method performs open-loop mode control of coil current of the electric stepper motor by setting the average voltage supplied to the electric stepper motor according to values computed from the step frequency, irrespective of the observed feedback current from the current feedback loop.