Abstract: Disclosed is a linear electric motor having a fixed primary comprising a stator divided into a number of sections, including a translating secondary having an operative length longer than any two adjacent sections of the stator in the form of a reaction plate, and a connecting means for connecting only those sections of the stator that are at least partially covered by the reaction plate. The position of the reaction plate relative to the stator is determined by monitoring current in the active representative sections. Power is supplied to each stator section individually, with power supplied in a modulated manner to end active stator sections only partially covered by the reaction plate. A measurement of the current to the active representative section is used to control output voltage to all energized stator sections and is used to determine the change in position of the reaction plate.

Abstract: A microcontroller determines the position of the rotor of a brushless, direct-current motor by determining the time of zero crossing of back electromotive force (EMF) emanating from the non-driven phase winding. The zero crossing point is determined by interpolating voltage differentials that are time stamped. Each voltage differential is the difference between the phase voltage of the phase winding and the motor neutral point voltage. The time of zero crossing is determined without using a comparator and without interrupting the processor at each zero crossing point. The processor interpolates the time of zero crossing independently of when the zero crossing point occurs. A hold signal conductor is connected both to a sample and hold circuit and to the load input lead of a time stamp register. The microcontroller simultaneously captures a phase voltage in the sample and hold circuit and a timer count in the time stamp register.

Abstract: In a back electromotive force phase detecting device, a timing generating unit generates a timing signal indicating a start timing, an intermediate timing and an end timing of a 180-degree electrical angle period in a detection target phase, from an excitation pulse signal. A difference calculating unit receives the timing signal, and calculates a difference between a total PWM control period of the detection target phase during a first-half 90-degree period, and a total PWM control period of the detection target phase during a second-half 90-degree period. In an excitation control device, a control unit changes the capability of driving a motor based on an output of the back electromotive force phase detecting device.

Abstract: The present invention relates to a drive apparatus and drive method for switching an energization mode when a voltage of a non-energized phase of a brushless motor crosses a threshold. In threshold learning, first, the brushless motor is stopped at an initial position. The brushless motor is then rotated by performing phase energization based on the energization mode from the stopped state. The voltage of the non-energized phase at an angular position of switching the energization mode is detected from a maximum value or a minimum value of the voltage of the non-energized phase during the rotation, and the threshold is learned based on the detected voltage. Alternatively, the brushless motor is positioned at the angular position of switching the energization mode by maintaining one energization mode, and then the energization mode is switched to the next energization mode.

Abstract: A sensorless starting control method for a brushless direct current (BLDC) motor, comprising a first rotor-positioning step configured to position a rotor in a first position by operating a coil unit in a first excitation state, a second rotor-positioning step configured to operate the coil unit in a second excitation state such that the rotor rotates from the first position to a second position, and an open-looped starting step configured to excite a plurality of coils of the coil unit in sequence so as to drive the rotor to rotate in a predetermined direction, wherein the coil unit generates a back electromotive force (EMF) when the rotor rotates in the predetermined direction. The method further comprises a close-looped operation step configured to control the BLDC motor to attain a predetermined rotational speed via a feedback of the back EMF.

Abstract: Information indicative of the placement of spindle motor components may be obtained and used to provide a correction to one or more BEMF-derived attributes used to control the spindle speed. In some implementations, first and second signals indicative of BEMF of different stator windings may be used to determine a speed-related characteristic. The speed related characteristic may be used to determine an error amount, which may be used to determine a correction factor to control the speed of the spindle motor.

Abstract: The invention relates to a method carried out with simple means for determining the position of the rotor in a sensorless and brushless multi-phase electric motor (1) in addition to a device particularly suitable for carrying out said method. According to said method, a phase voltage (Uv) on the clamping side on said motor phase is to be detected after clamping a first motor phase (V) from the reference potentials (UZ,M) of an intermediate circuit (7) during a detection period (TE), via which the detection period (TE) determines a peak value (Uv*) of the detected phase voltage (Uv), the peak values (Uv*) are to be compared to the comparative value (Uc), and a positon signal (SP) is to be produced when the peak value (Uv*) exceeds the comparative value (U0).

Abstract: The present invention provides a motor drive apparatus which improves a trade-off relation between a stable position detection and noise at its driving. A sensorless drive operation circuit calculates by operation a zero cross point (point p) of a voltage of a position detection phase at the next interval, using time information measured based on an output signal from a comparison circuit at the previous interval and the present interval. After the point p has been calculated, points a and b are detected by interrupting a predetermined time drive current.

Abstract: A negative sequence feedback circuit is connected to monitor and minimize unbalances in a high-frequency ac carrier signal provided to a motor/load for the purpose of detecting rotor position. The negative sequence feedback circuit detects unbalances in the high-frequency ac carrier signal and generates negative sequence feedback. The feedback is combined with command signals used to generate the high-frequency ac carrier signal, and the combination of the command signals with the negative sequence feedback is provided to an inverter for generation of the high-frequency ac carrier signal, wherein the negative sequence feedback reduces unbalances in the resulting high-frequency ac carrier signal such that a balanced high-frequency carrier signal is provided to the motor/load.

Abstract: Disclosed herein is a sensorless-type brushless DC motor, including: a magnet provided in a rotor; and a stator formed by winding a coil on a core stacked with sheets while facing the magnet, wherein the position of the rotor is detected by detecting back electromotive force induced to the coil, the back electromotive force includes a harmonic component 5 times higher than a fundamental wave, and an amplitude ratio of the 5-times harmonic wave to the fundamental wave is set to be 1% or more. Further, the sensorless-type brushless DC motor can prevent a failure in detecting an initial position of the rotor by controlling a waveform of the back electromotive force and minimize an increase of a starting time.

Abstract: A method for determining the position at rest of a rotor of a machine having at least one excitation winding. The invention provides a technique for detecting the position of the rotor at rest, from information contained in the voltages produced at the terminals of the stator windings, when the voltage applied to the rotor winding undergoes variations. The invention thus makes it possible to detect the rest position of the wound-rotor machine in the absence of ordinary position sensors such as magnetic, optical, resolving, mechanical, capacitive or other sensors.

Abstract: Methods, systems and computer program products for compensating repeatable timing variations associated with a spindle motor are described. Specifically, a repetitive error correction factor may be determined using a computational model which predicts timing variations. The correction factor can then be used to cancel the effect of the actual timing variations upon the spindle motor.

Abstract: An energization timing determination circuit corrects a shift contained in a position signal outputted from a position detecting means and supplies energization timing appropriate to drive a motor. A correction amount computation unit computes detection intervals obtained based on position signals outputted from filters, comparators, and a position detection unit during one cycle of electrical angle. The correction amount computation unit thereby determines the duty shift length ? and phase shift length ? of the position signals. A control circuit corrects energization timing based on the position signals according to the detected shift lengths.

Abstract: There is provided an electromechanical machine control system for variable speed controlling an electromechanical machine which can realize a desired control response and a stable control system by online regulating the gain of a linear differential controller by current feedback based on an electric parameter or mechanical parameter of the electromechanical machine. The electromechanical machine control system includes a current coordinate transformer (15) for coordinate transforming a current detection value of the electromechanical machine (13) which is inputted into a ?-axis current having the same phase as a position reference and a ?-axis current which advances 90 degrees further than the position reference, a ?-axis stabilizer (16) for implementing a linear differential control on the ?-axis current which is inputted to output a ?-axis current voltage correction amount and a ?-axis stabilizing gain regulator (17) for regulating the linear differential control gain of the ?-axis stabilizer.

Abstract: A rotor position detecting circuit includes a first position detecting circuit having a low-pass filter that shapes up phase voltage induced in a phase coil and a first comparator that compares the output voltage of the low-pass filter with a threshold level to form a first rotor position signal, and a second position detecting circuit having a second comparator that compares the phase voltage with a threshold voltage and a control unit that digitally processes the output voltage of the second comparator to form a second rotor position signal. The control unit corrects the first rotor position signal by the second rotor position signal to provide a final rotor position signal when the rotation speed of the brushless DC motor is in a measurable range.

Abstract: Provided is a motor having a combination of a plurality of coil pairs and a permanent magnet, wherein these coil pairs are supplied with an excitation signal from a drive circuit so as to be excited at alternate opposite poles, and the permanent magnet is constituted such that the plurality of polar elements is disposed to become alternating opposite poles; the drive circuit is constituted to supply an excitation signal having a prescribed frequency to the coil pairs, and relatively move the coil pairs and permanent magnet with the magnetic attraction—repulsion between the coils and permanent magnet; and the drive circuit is constituted to supply to the coil pairs a waveform signal corresponding to the pattern of the back electromotive voltage to be generated in accordance with the relative movement between the coil pairs and permanent magnet.

Abstract: A method for driving a two-phase brushless motor is disclosed. The motor includes a rotator with permanent magnetism and a stator including a first coil and a second coil. The method includes activating the two-phase brushless motor, detecting an output voltage of a disabled coil of the first coil and the second coil to generate a detection result, comparing the detection result and a reference voltage to determine a commutation time point between the first coil and the second coil, generating a commutation signal according to the commutation time point, and driving the two-phase brushless motor according to the commutation time point.

Abstract: A method of controlling a motor connected to an unbalanced load in accordance with an embodiment of the present application includes operating the motor for a predetermined period of time with a first performance parameter held constant, monitoring a signal related to a second performance parameter, monitoring electrical rotation within the motor and providing an electrical rotation signal indicative of the electrical rotation angle, sampling the signal related to the second performance parameter at a predetermined angle of electrical rotation, arranging samples provided in the sampling step in predetermined order and generating a mechanical rotation signal representing the mechanical rotation angle of a rotor of the motor based on the arrangement of samples. The mechanical rotation signal is used to control at least one of the first and second performance parameters of the motor.

Abstract: An electrically operated hydraulic pump having a pump portion and a motor portion includes rotation controlling means controlling rotation of a rotor, first rotor position detecting means detecting rotational position of the rotor on the basis of speed electromotive force induced by exciting coils, second rotor position detecting means detecting the rotational position of the rotor on the basis of magnetic field of a magnet provided at the motor portion, and motor operating condition detecting means detecting operating condition of the motor portion. The rotation controlling means switches a first rotation controlling based on the rotational position of the rotor detected by the first rotor position detecting means, and a second rotation controlling based on the rotational position of the rotor detected by the second rotor position detecting means, on the basis of a result detected by the motor operating condition detecting means.

Abstract: An apparatus and a method for driving a sensorless motor are described and shown in the specification and drawings, where the method includes steps as follows. First, a control signal is acquired, where the control signal has information of a predetermined rotational speed. Next, energy is supplied and progressively increased to the sensorless motor, so as to rotate a rotor of the sensorless motor. Then, a position of the rotor is detected. Finally, the energy is gradually regulated so that the sensorless motor is maintained at the predetermined rotational speed.

Abstract: A disk drive system including retract logic for control of the voice coil motor in a retract operation, in which the voice coil motor positions the read/write head actuator arm in a safe place in a loss-of-power event, is disclosed. The retract logic includes circuitry for controlling the application of power to the voice coil motor from an external capacitor, so that a constant voltage is maintained across the voice coil motor. Current from the capacitor is directed to an internal variable resistor that conducts a selected current, in parallel with the current applied to the voice coil motor. The voltage developed across the variable resistor is applied to one input of a control amplifier, which receives the voltage across the voice coil motor at another input; the control amplifier in turn controls the gate of a low side transistor. The transistor passes current to the extent that the voltage across the voice coil motor corresponds to that developed across the variable resistor.

Abstract: The idle-stop restart control system includes: a sensorless synchronous motor-generator which operates as a generator and a starting motor; an induced-signal detecting circuit for detecting an induced signal output from an armature winding; a field drive circuit for controlling energization of a field winding; and a restart control circuit output, to the field drive circuit, a drive signal for controlling the energization of the field winding to amplify the induced signal while calculating the number of revolutions and an angular position of a rotor based on the detected induced signal when an engine stop command is input and a level of the detected induced signal is equal to or less than a predetermined value and output the drive signal for controlling the energization of the armature winding to restart the engine based on the calculated number of revolutions and angular position of the rotor when a restart command is input.

Abstract: It is determined which of six continuous sections having different magnitude correlation of signal amplitude of each phase of an input three-phase signal a section is. Predetermined subtraction is performed between respective phases in the section, to obtain a normalized amplitude value normalized in the section, using the subtraction result. The normalized amplitude value is converted to a vector phase for one cycle based on a predetermined phase and output corresponding to the determined section.

Abstract: This invention relates to the control of electrical machines and is concerned more particularly, though not exclusively, with the control of flux switching electrical machines without a mechanical shaft position sensor.

Abstract: The invention relates to a frequency converter, and also to a method for determining the position of the rotor of an electric machine. The frequency converter comprises a load bridge and also a control of the load bridge, for supplying electricity between the load bridge and an electric machine connected to the load bridge. The frequency converter comprises a determination for at least one electrical parameter of the aforementioned electric machine, and the frequency converter comprises a determination for the position of the rotor of the aforementioned electric machine. The load bridge is fitted to supply a first alternating electricity excitation signal, which is formed in relation to the electrical angle of the electric machine, to the aforementioned electric machine.

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: An information handling system includes a three phase brushless direct current motor and a motherboard which in turn includes a drive circuit. The three phase brushless direct current motor is configured to rotate a cooling fan in the information handling system based on a control signal. The drive circuit is connected to the three phase brushless direct current motor, and the drive circuit is configured to adjust the control signal sent to the three phase brushless direct current motor based on a back electromagnetic flux signal.

Abstract: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: A method for controlling the firing angle of a single-phase AC powered electric motor is provided which is triggered by at least one locking electronic switch, such as a triac (T1 and T4) located between the distribution voltage (UV) and at least one motor winding (A, B). According to said method, intervals are defined within which the triacs (T2 to T4) are to be fired according to the curve of the distribution voltage (UV) and the voltage (UEMK) induced in the respective winding in order to allow the motor to start as quickly and smoothly as possible and run quietly and at high efficiency.

Abstract: A method of tuning a DC brushless motor, wherein measurement of back EMF voltage is used to detect changes in the torque requirements caused by variation in the operating conditions of the DC brushless motor, the method including varying the timing of the driving signals to the motor to compensate for the changes in the torque requirements.

Abstract: A back electromotive detection comparator compares back electromotive voltages Vu to Vw with a common voltage Vn of coils, and generates first rectangular wave signals Pu to Pw. A masking circuit performs masking of the first rectangular wave signals Pu to Pw, and outputs the resultant signals as second rectangular wave signals Mu to Mw. An output circuit supplies a drive current to coils on the basis of the second rectangular wave signals Mu to Mw. A frequency generating circuit generates a frequency generation signal SigFG whose level switches at every edge of the second rectangular wave signals Mu to Mw. A mask signal generating circuit generates a mask signal MSK which is at a high level during an interval multiplied by a coefficient to a pulse width Tp of the frequency generation signal SigFG after level transition of the frequency generation signal SigFG.

Abstract: A method and apparatus for electronic control of a direct current motor is disclosed based upon a sensorless commutation technique using voltage vector analysis. A voltage vector is produced by addition of supply phase voltage vectors of energized windings with the back-electromotive force vector of the unenergized winding. The resultant voltage vector rotates at the same speed as the rotor and possesses rotor position information used to commutate phase windings. The angle that the resultant voltage vector makes with the real axis is measured to commutate the phase windings. By parking the rotor in a predetermined position, this technique can be used to efficiently start the motor from rest and commutate phase windings during normal operation.

Abstract: A control device of a boost converter which includes: an inverter circuit which controls switching to apply current to a stator winding of respective phases of a multi-phase brushless DC motor; and a boost circuit which is provided on an input side of the inverter circuit and has at least a reactor and a switching element, and controls ON and OFF states of the switching element of the boost circuit on the basis of a boost voltage command which is a command for boost voltage output from the boost circuit, the control device is provided with a boost voltage command setting unit which sets the boost voltage command on the basis of counter electromotive voltage of the brushless DC motor and a torque command for the brushless DC motor.

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: Analog control of the pulse width used to control the speed of a voice coil motor may be implemented using a “constant-current-charging-capacitor” configuration where the time needed to charge the capacitor is directly related to how far the actual motor speed is from the target speed. The BEMF voltage, indicative of motor speed, is sampled, and then stored in a storage capacitor, which is allowed to charge/discharge to a target voltage level. The time required to charge/discharge the capacitor to the target voltage is directly proportional to the difference between the BEMF voltage and the target voltage, and may be used directly as the pulse width (i.e., the charging time) in the PWM velocity control system. To avoid larger capacitors, a pulse multiplier circuit can be added, allowing charging/discharging the sampled voltage to the target voltage to be repeated by a number, N, of times.

Abstract: A stepper motor apparatus controls a stepper motor by taking a maximum response speed and maximum response acceleration of the stepper motor into account.

Abstract: A method and a circuit are provided for the commutation of brushless direct-current motors (BLDC motors), without using sensors, and especially to a method and a circuit for producing rotor position signals, without using sensors, for the commutation of brushless direct-current motors. In the method and the circuit Hall sensor signals are emulated without sensors and rotor position signals free of disturbing pulses and with a correct phase position are generated from said signals. The rotor position signals can be used to carry out a reliable, sensor-free commutation.

Abstract: A surgical motor control device for controlling a surgical drive unit comprises a sensorless electric motor with M motor windings. The motor control device is configured to perform a method for controlling the drive unit. The motor control device be configured to control the drive unit using a multiphase PWM method. An improved method for controlling a surgical drive unit and an improved surgical drive system are also proposed.

Abstract: In a motor having a number of poles that have nominally equiangularly-spaced positions that in fact deviate from those positions, the actual periods between zero-crossings of the back-EMF generated during pole-pair interactions are measured. The ratios of the various pole periods can then be computed, and the motor drive profile can be adjusted for each pole by applying the respective ratio to fit samples of the back-EMF profile to each respective pole.

Abstract: An image forming apparatus includes: a light source that emits a light beam; a photosensitive member; a driving motor; a rotary polygon mirror, which is rotated by the driving motor, and which periodically deflects the light beam emitted from the light source to sequentially form scanning lines on the photosensitive member; a position detecting unit, which detects a rotational position of the driving motor, and which outputs a detection signal; a sensor, which receives the light beam deflected by the rotary polygon mirror, and which outputs a light receiving signal; a detecting unit, which receives the detection signal and the light receiving signal, and which detects a rotation direction of the driving motor based on a timing pattern of a detection of the rotational position of the driving motor and a reception of the light beam by the sensor.

Abstract: The present invention provides a simple, robust, and universal position observer for use with sensorless synchronous machines. The observer may be implemented using an equivalent EMF model of a synchronous machine or, alternately, using a sliding mode controller based on the equivalent EMF model of the synchronous machine. The observer may be used on any type of synchronous machine, including salient or non-salient pole machines such as a permanent magnet, interior permanent magnet, wound rotor, or reluctance synchronous machine. The observer provides low sensitivity to parameter variations and disturbances or transient conditions in the machine. In addition, no knowledge of speed is required as an input to the observer and an estimated position may be calculated using a subset of the machine parameters.

Abstract: An inverter controller for driving a brushless DC motor, of which rotor is provided with permanent magnets, includes an inverter circuit, a position sensing circuit, a DC voltage sensor, and a conduction angle controller. The inverter circuit is connected to the brushless DC motor for driving this motor. The position sensing circuit senses a rotor position with respect to a stator from an induction voltage of the brushless DC motor. The DC voltage sensor senses a voltage value of a DC power voltage supplied to the inverter circuit. The conduction angle controller changes a conduction angle of the inverter circuit within a range less than 180 degrees in electric angles in response to a rate of change in the DC power voltage.

Abstract: A DC motor comprises a stator having at least three windings coupled to a neutral point; a first pair of upper and lower switches for driving a first winding of the at least three windings to a first voltage or in tristate; a second pair of upper and lower switches for driving a second winding of the at least three windings to a second voltage or in tristate; a third pair of upper and lower switches for driving a third winding of the at least three windings to a third voltage or in tristate, one of the first, second or third windings being in tristate; a back electro-motive force (BEMF) signal generation circuit coupled to receive a BEMF voltage from the winding in tristate; a comparator coupled to receive the BEMF voltage and a zero-crossing voltage representing the voltage at the neutral point at a predetermined time and for comparing the BEMF voltage and the zero-crossing voltage to generate a comparison result; a zero-crossing voltage generation circuit to output the zero-crossing voltage to the comparato

Abstract: Method for control of synchronous electrical motors that enables determining continuously in time the motor load angle and speed of rotation without using additional rotor position sensors. The method is realized with solving the set of differential equations that govern the currents and the voltages in the stator windings of the motor for the time intervals between each two consecutive reachings of the currents in the windings to their set values and deriving relationships between the induced in the windings back-electromotive force voltages and the parameters of the Pulse Width Modulation. The parameters of the Pulse Width Modulation are measured and stored in memory and based on the derived relationships the values of the back-electromotive force voltages are calculated at every moment in time and from these values subsequently the values of the load angle and the angular rotor speed of the motor are calculated.

Abstract: Embodiments of the present invention permit the optimization of torque control of a permanent magnet machine including obtaining instantaneous terminal voltages of the machine, transforming the instantaneous terminal voltages to a zero direct axis voltage and a non-zero quadrature axis voltage, using a mathematical transformation, regulating the electrical frequency of the permanent-magnet machine such that the zero direct-axis voltage is adjusted to have a value of zero, determining a non-final electrical angle of the permanent-magnet machine by applying an integrator to the regulated electrical frequency of the machine, determining a final electrical angle of the of the machine by integrating the non-final electrical angle and an electrical angle from a previous calculation cycle, and regulating the current vector of the machine such that the current vector is perpendicular to the final electrical angle of the machine, thereby optimizing the torque of the machine.

Abstract: A particularly high level of performance in a sensorless, electronically commutated multiphase electric motor can be achieved, wherein for one full cycle at least, one motor phase is controlled in an asymmetrical manner relative to a further motor phase by controlling a commutation angle of one motor phase by reduction relative to a corresponding commutation angle of the other motor phase. Alternatively or in addition, according to the aforementioned method, at least one motor phase is asymmetrically controlled by reduction by self-reference for a full cycle, a commutation angle being controlled by reduction relative to a preceding or subsequent commutation angle or the size of the intermediate angles between two commutation angles being varied, the reduced commutation angle always being preceded or followed by a measurement angle within which the relevant motor phase is switched at zero current for detecting the rotor position by measuring the counter-electromotive force.

Abstract: A method is provided for managing at least one transition in a three-phase BLDC motor describing a cycle including six successive states, wherein the motor obtains first, second and third synchronization signals. The synchronization signals are respectively associated with first, second and third coils of the motor. The method includes the following steps, for each current transition associated with the switching of the motor from a current state to a next state: selecting a current synchronization signal on which the current transition is to appear; detecting the occurrence of the current transition on the current synchronization signal; and sending, to the motor, at least one current control signal so as to switch the motor from the current state to the next state.

Abstract: A method and apparatus for electronic control of a direct current motor is disclosed based upon a sensorless commutation technique using voltage vector analysis. A voltage vector is produced by addition of supply phase voltage vectors of energized windings with the back-electromotive force vector of the unenergized winding. The resultant voltage vector rotates at the same speed as the rotor and possesses rotor position information used to commutate phase windings. The angle that the resultant voltage vector makes with the real axis is measured to commutate the phase windings. By parking the rotor in a predetermined position, this technique can be used to efficiently start the motor from rest and commutate phase windings during normal operation.

Abstract: A rotor position detection circuit detects a position of a rotor in a motor from a detection signal of an induced voltage generated in a stator coil. The circuit includes: a first low pass filter having a first reference potential for filtering the detection signal; a comparator for comparing an output signal from the first low pass filter with a predetermined reference voltage and for outputting a rotation position signal; and a second low pass filter having a second reference potential for filtering a virtual neutral point potential of the motor. The first reference potential is the filtered virtual neutral point potential, and the second reference potential is a ground.

Abstract: A motor control system includes a power control module and a detection module. The power control module controls power applied to first and second stator coils of a motor to rotate a rotor. The rotor induces voltages in the first and second stator coils when the rotor is rotating. The detection module determines a first time when a first voltage is induced in the first stator coil and determines a second time when a second voltage is induced in the second stator coil after the first voltage is induced. The detection module determines a speed of the rotor based on a difference between the first and second time. The power control module applies current through the second stator coil a predetermined period after the second time. The power control module determines the predetermined period based on the speed of the rotor.