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: There are provided a motor driving control apparatus and method, and a motor using the same. The motor driving control apparatus includes: an inverter unit applying a driving current to a motor apparatus according to a driving control signal; a back-electromotive force detecting unit detecting back-electromotive force generated by driving of the motor apparatus; a driving current change unit reflecting a level of the back-electromotive force to determine a resistance value and reflecting the resistance value in the driving current; and a controlling unit performing a control operation to change the driving control signal using the driving current in which the resistance value is reflected and the back-electromotive force.

Abstract: The invention relates to a method for providing a trigger signal in response to the commutation of a mechanically commutated electric motor (1). The method comprising the steps of providing a mechanically commutated electric motor (1), providing a power supply for said mechanically commutated electric motor via electrical supply leads (10, 11) from power supply circuitry, providing a filter (15) connected to said electrical supply leads (10, 11), detecting with said filter (15) a voltage spike occurring at commutation, outputting from said filter (15) said trigger signal.

Abstract: A sensorless motor controller includes a variable link control, including a radiation-hardened field programmable gate array (FPGA) and a back electromotive force (EMF) decoder circuit. The back EMF decoder infers the position of a rotor of the motor. A filter on the decoder conditions the back EMF signal and has multiple cutoff frequencies which can be dynamically controlled by the FPGA in order to compensate for phase shift in the back EMF signal. The FPGA also controls a variable DC link and its digital speed control loop.

Abstract: A method for operating an electric motor with primary and secondary sections, wherein the primary section has a multi-phase exciter winding, each of the phase connections of said exciter winding being connected to an output connection of an end stage, which has controllable semi-conductor switches for applying phase voltages to the output connections, includes the following steps: a) introducing an operating phase by applying the phase voltages to the output connections such that a moving magnetic field is induced in the exciter winding, the moving field effecting a relative motion between the primary and secondary sections, b) hinting off the phase voltage at least one of the output connections to introduce a measurement phase, and c) measuring the electrical back emf induced in the winding strand in order to determine the angular difference between the phase position of the exciter current and that of the back emf.

Abstract: In a multi-phase brushless DC motor, a zero crossing N-bit filter includes a comparator and a phase multiplexer. The phase multiplexer connects each motor phase to each of a positive and a negative input of the comparator, with a switch in each connection to form a switch array. A microprocessor is disposed to operate the switches, and is configured to measure a BEMF for a first phase by opening the switches connecting all other phases to the positive input of the comparator and by opening the switch connecting the first phase being measured to the negative input of said comparator. The comparators output is received by a shift register. The microprocessor is configured to respond to a zero crossing when a majority of bits in the shift register change between high and low.

Abstract: A driving circuit for a single-phase brushless motor includes: a driving-signal-generating circuit to generate a driving signal for supplying first and second driving currents to a driving coil of the single-phase brushless motor in an alternate manner with a de-energized period therebetween; an output circuit to supply the first or the second driving current to the driving coil in response to the driving signal; and a zero-cross detecting circuit to detect a zero cross of an induced voltage, generated across the driving coil, during the de-energized period, wherein the driving-signal-generating circuit determines a length of a subsequent energized period, based on a driving cycle from a start of an energized period to a time when the zero-cross detecting circuit detects the zero cross, and the zero-cross-detecting circuit starts detection of the zero-cross after a predetermined time period has elapsed from a start of the de-energized period.

Abstract: A method for controlling a discharge pump of a household appliance, including starting a synchronous electric motor that actuates said discharge pump until the synchronism condition is reached, and driving said synchronous electric motor at a steady state through phase control by varying the firing angle (?). In driving said synchronous motor at steady state through phase control, said firing angle (?) is feedback controlled to cancel the phase difference between the mid-point of a zero current plateau of a function of the phase current fed to the electric motor and the zero-crossing point of a counter electromotive force signal (fcem) relative to the same phase. In feedback controlling the firing angle (?), the synchronous electric motor is switched off if the required firing angle (?) exceeds a maximum threshold (?lim), which may result from the operation of the discharge pump in air-water conditions.

Abstract: There are provided a back electromotive force detection circuit, and a motor driving control apparatus and a motor using the same. The back electromotive force detection circuit includes: a voltage generating unit generating a voltage in inverse proportion to a duty ratio of a pulse width modulation (PWM) signal; a variable amplifier controlling a gain according to the voltage generated by the voltage generating unit, and amplifying back electromotive force according to the controlled gain; and a comparator comparing an output from the variable amplifier with a pre-set reference signal, and outputting a zero-crossing signal of the back electromotive force.

Abstract: There are provided a motor driving apparatus and method, the motor driving apparatus including a current detecting unit detecting a level of a driving current applied to a motor for each predetermined period, a current comparing unit comparing the level of the driving current detected by the current detecting unit in a previous period and the level of the driving current detected by the current detecting unit in a current period, and a controlling unit adjusting a level of a reference signal compared with a back electro motive force (BEMF) signal of the motor based on an output of the current comparing unit.

Abstract: There are provided a motor driving control apparatus, a motor driving control method, and a motor using the same. The motor driving control apparatus includes a driving signal generation unit, a back electromotive force detection unit, and a frequency controller. The driving signal generation unit may generate a driving control signal for controlling driving of a motor device. The back electromotive force detection unit may detect back electromotive force of the motor device. The frequency controller may provide control to estimate a zero crossing point of the back electromotive force, set a frequency modulation section including the zero crossing point, and modulate a frequency of the driving control signal during the frequency modulation section.

Abstract: In an electronic commutation method in direct current electric motors which are controlled by pulse width modulation of the energization which takes place periodically with positive and negative current values and intermediate energization pauses, the counter-induction voltage is measured, wherein the zero crossing of the counter-induction voltage is determined by means of the point of intersection of the envelope to the counter-induction voltage with the zero line. The pulse width modulation of the energization is changed if the zero crossing is covered by positive or negative current values of the energization.

Abstract: There are provided a motor driving control apparatus and method, and a motor using the same. The motor driving control apparatus includes: a back-electromotive force detecting unit detecting back-electromotive force generated in a motor apparatus; a zero-crossing calculating unit sampling the back-electromotive force and determining a zero-crossing point using an average value of adjacent sections in the sampled back-electromotive force; and a controlling unit controlling driving of the motor apparatus using the zero-crossing point.

Abstract: There are provided a motor driving control apparatus and method and a motor using the same. The motor driving control apparatus includes: a back-electromotive force detecting unit detecting back-electromotive force of a motor apparatus; a gradient calculating unit calculating a gradient of a waveform of the detected back-electromotive force; and a controlling unit calculating a zero-crossing point of the back-electromotive force using the calculated gradient and controlling driving of the motor apparatus using the calculated zero-crossing point.

Abstract: A method of controlling a brushless motor that includes rectifying an alternating voltage to provide a rectified voltage, and exciting a winding of the motor with the rectified voltage. The winding is excited in advance of predetermined rotor positions by an advance period that is updated in response to a zero-crossing in the alternating voltage. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: There are provided a motor driving apparatus and method, the motor driving apparatus including: a filter controlling unit detecting a frequency of a pulse width modulation (PWM) signal and generating a control signal; a first filtering unit filtering a back electromotive force (BEMF) signal according to the control signal; a second filtering unit filtering a reference signal according to the control signal; and a comparing unit comparing output of the first and second filtering units and generating a motor rotor detection signal.

Abstract: In a drive control circuit of a linear vibration motor, a drive signal generating unit generates a drive signal used to alternately deliver a positive current and a negative current to a coil. A driver unit generates a drive current in response to the drive signal generated by the drive signal generating unit and supplies the drive current to the coil. An induced voltage detector detects an induced voltage occurring in the coil. After a running of the linear vibration motor has terminated, the drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the motor running; this drive signal of opposite phase includes a high impedance period during which the driver unit is controlled to a high impedance state. The induced voltage detector detects the induced voltage occurring in the coil during the high impedance period.

Abstract: In a drive control circuit of a linear vibration motor, the drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the motor running, after the running of the linear vibration motor has terminated; this drive signal of opposite phase includes a high impedance period during which the driver unit is controlled to a high impedance state. An induced voltage detector detects an induced voltage occurring in the coil. A comparator has a function as a hysteresis comparator in which the output level does not vary in a predetermined dead band, and the comparator outputs a high-level signal or a low-level signal during the high impedance period. When an in-phase signal is consecutively outputted from the comparator during the consecutive high-impedance periods, the drive signal generating unit determines that the linear vibration motor has come to a stop.

Abstract: Speed of a motor, generator or alternator, more particularly the speed of an alternating current (AC) induction motor is determined. Problems associated with previous devices are overcome by providing a speed monitoring device that is readily retrofitted to an existing motor. A test signal is superimposed onto an input voltage, which voltage in use is applied to at least one winding of the stator of a motor (the test signal is at a frequency substantially equal to the rotor frequency). The test signal frequency is varied so that it varies from a minimum frequency to a maximum frequency. A current monitor monitors a resultant current, in the at least one stator winding. and deriving from the resultant current is a signal indicative of the rotor frequency.

Abstract: A method and device for controlling an electric motor, in particular a machine tool drive, wherein during a sensorless open-loop control mode of operation of the electric motor the speed and the torque are determined from the motor current and the motor voltage, and the moment of inertia of the electric motor torque are determined from the determined motor current and the determined motor voltage, wherefrom then a control torque is determined, which is then associated with an open-loop torque control value and supplied as the torque setpoint value to a control element for setting the motor current and/or the motor voltage in the open-loop mode of operation. As long as the speed is below a minimum speed, the control element receives as input variable a control or pilot control torque generated from a predefined moment of inertia for a sensorless closed-loop control mode of operation of the electric motor.

Abstract: A sensorless permanent magnet motor system that prevents negative torque caused by back EMF. The system determines the position of the rotating permanent magnet by monitoring back EMF generated on an inactive coil of the motor system. A snubber circuit is used to prevent the back EMF from causing negative torque on the motor. The voltage of back EMF used to power a logic circuit, such as a microcontroller, that controls the operation of the motor. The microcontroller controls the operation of the motor by detecting back EMF and is also partially powered by the back EMF.

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

Abstract: A zero crossing of a motor current waveform at the terminal of a brushless sensor-less multi-phase DC motor is determined without opening a non-drive period while the motor is continuously driven. A voltage level at a first threshold at the terminal of a motor is detected. At a first time, a current flow switch connected to the terminal is switched. At a second time, a voltage level at a second threshold is detected at the terminal of the motor. The zero crossing is determined between the first time and the second time and used to synchronize the driving of the motor.

Abstract: A zero-cross detection unit monitors an AC voltage detected by a voltage sensor, generates a zero-cross point signal when the voltage crosses 0V, and supplies the signal to a controller. A rotation number setting unit sets a rotation number command to serve as a target of a synchronous motor. A rotation number correction coefficient data table stores correction coefficient data for a target rotation number. A correction coefficient data extraction unit extracts correction coefficient data in accordance with an elapsed time of the zero-cross point signal generated by the zero-cross detection unit from a rotation number correction coefficient data table, and outputs the data to a corrected rotation number creation unit. The corrected rotation number creation unit corrects the rotation number set by the rotation number setting unit in accordance with the extracted correction coefficient data, and outputs the corrected rotation number to a sine wave data creation unit.

Abstract: A digital signal processor (DSP) is operable to receive a single-phase back electromotive force signal (back-EMF) fed back from a motor and control an inverter for driving the motor based on the single-phase back-EMF signal. The DSP includes an electrical angle building module, a rotation speed control module, and a pulse width modulation control module. In addition, the DSP further includes a field-weakening compensation module. The field-weakening compensation module is operable to automatically regulate an electrical angle based on a rotation speed of the motor and a set of predetermined compensation parameters so that the DSP can be operable to achieve an adaptive control. Furthermore, a motor control system and method are disclosed herein.

Abstract: Disclosed is a current source inverter device which controls the power factor in an arbitrarily configurable manner without a magnetic pole position detector. The device is provided with a current source inverter; a motor supplied with alternating current power from the current source inverter; and a control means which detects the terminal voltage of the motor, calculates the motor's internal induced voltage and the motor current that flows in the motor based on the detected terminal voltage, and controls the current source inverter. The control means calculates the phase difference (?c) between the terminal voltage and the motor current, the phase difference (?x) between the motor current and the internal induced voltage, and the phase difference (?v) between the terminal voltage and the internal induced voltage.

Abstract: The invention relates to an electrical power tool, particularly an electric hand power tool, for operating with alternating current, having an electric motor, and electronic control device, and an electrical power switch for actuating the electric motor, wherein the electronic control device comprises a bias voltage output and a detection input, connected to each other by means of a voltage divider comprising a summation point and to the side of the power switch facing the electric motor, and the control device is further designed such that the potential at the detection input is monitored after actuating the power switch and used for checking whether the power switch is conducting, and that it is actuated again if the power switch was not conducting or returned to the non-conducting state during the monitoring, and that said checking and any renewed actuation of the power switch is repeated within a half-wave of the alternating voltage.

Abstract: A driving circuit for a single-phase-brushless motor includes a driving-signal-generating circuit to generate a driving signal for supplying, to a driving coil of the single-phase-brushless motor, first- and second-driving currents alternately with a de-energized period therebetween, an output circuit, and a zero-cross-detecting circuit.

Abstract: The brushless motor driver includes a sample and hold circuit which samples and holds a first value of the first comparison signal in a first case in which a current is forced to flow from a first phase coil of the three-phase brushless motor to a second phase coil and no current is forced to flow to a third phase coil in a first period having a preset setting time and a second value of the first comparison signal in a second case in which a current is forced to flow from the second phase coil to the first phase coil and no current is forced to flow to the third phase coil in a second period having the preset setting time subsequent to the first period. The brushless motor driver includes an addition circuit which adds up the first value and the second value sampled and held by the sample and hold circuit and outputs an addition signal depending upon a result of the addition.

Abstract: To achieve peak acoustic and power performance, the coil or applied current should be in phase or substantially aligned with the back electromotive force (back-EMF) voltage. However, there are generally phase differences between the applied current and back-EMF voltage that are induced by the impedance of the brushless DC motor (which can vary based on conditions, such as temperature and motor speed). Traditionally, compensation for these phase differences was provided manually and on an as-needed basis. Here, however, a system and method are provided that automatically perform a commutation advance by incrementally adjusting a drive signal over successive commutation cycles when the applied current and back-EMF voltage are misaligned.

Abstract: During operation of a 3 phase BLDC motor it is driven by use of a PWM waveform applied to one of the driven phase (curve a). The other driven phase is connected thereto but no driving signal is applied (curve b). The third phase is left floating (curve c). This allows the back EMF in the third phase to be monitored for the purpose of determining rotor position by detection of zero crossing points. The rapid switching of the PWM pulses causes ringing in the back EMF signal indicated for one pulse by the ringed portions 1 of curve c. The ringing in the back EMF signal introduces inaccuracy into position calculations derived from back EMF signal measurement. In order to reduce this ringing, in the present invention, a reverse pulse is applied to the other driving coil shown (curve b) prior to a PWM on pulse. The reverse pulse has a polarity such that it drives the phase current through the linked coils in a direction opposite to that caused by the PWM on pulse.

Abstract: A motor control circuit and associated techniques detect a zero crossing of a current in a motor winding by detecting a revers current in a half bridge circuit used to drive the motor winding.

Abstract: Systems and methods for generating a signal useful in the commutation of current through windings of brushless direct current electric motors are provided. Such methods comprises detecting a kickback pulse in a non-driven winding of a motor; detecting a rotor-induced zero crossing in the non-driven winding following the detection of the kickback pulse; and using the detection of the rotor-induced zero crossing to generate a signal useful in commutation of the motor.

Abstract: The invention relates to a method for the sensorless commutation detection of electronically commutated electric motors, in which the phase current is interrupted for a blanking time in order to detect the zero passage. On the basis of the profile of the mutual induction voltage, a decay time, which is characteristic for a decay of the phase current, is determined within the blanking time and the start of the blanking time is determined as a function of the time difference between the decay time and the end of the blanking time.

Abstract: A drive control signal generating circuit that generates a drive control signal for driving a motor includes an output control circuit that includes a flip-flop in which a state changes by a rotational state signal of the motor crossing a reference value and generates a motor drive control signal according to the state of the flip-flop, a clock generating circuit that generates a clock that defines a time of reading data in the flip-flop of the output control circuit; and a PWM conversion circuit that PWM-converts the drive control signal using the clock as a PWM signal. The clock has a frequency in which the output control circuit operates and has a duty ratio of the PWM signal.

Abstract: Regarding a brushless motor control device and a control method, the phase voltage Vsu of any one phase of the three-phase brushless motor is detected by a sub-coil (Su) (6). A time interval between adjacent zero-cross points a1 and a2 thereof is measured. Based on the time interval between the zero-cross points, a time T/3 and a time 2T/3 are calculated. Then, based on the time t/3 and the time 2T/3, phases of zero-cross points b1 and c1 of the two other phases are estimated. Then, based on the estimated zero-cross points b1 and c1, phases of the phase voltages of the two other phases are estimated, thereby controlling conduction on each phase coil of the three-phase brushless motor.

Abstract: A method of controlling a brushless motor that includes rectifying an alternating voltage to provide a rectified voltage, and exciting a winding of the motor with the rectified voltage. The winding is excited in advance of predetermined rotor positions by an advance period and is excited for a conduction period over each electrical half-cycle of the motor. The length the advance period and/or the conduction period is defined by a waveform that varies periodically with time. The method then includes adjusting the phase of the waveform relative to the alternating voltage in response to a change in one of motor speed and RMS value of the alternating voltage. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A motor driving apparatus and a refrigerator using the same is provided. The refrigerator may include a compressor, a motor, a driving unit, temperature sensing units sensing the temperatures of storage chambers and an external temperature, and a control unit selecting a driving mode of the driving unit based on the sensing result of the temperature sensing units and controlling the driving unit to drive the motor according to the selected driving mode. In a general operation mode, the control unit controls the driving unit to drive the motor in a 120 degree conduction method, and in a power-saving operation mode, the control unit controls the driving unit to drive the motor in a 90 degree conduction method. The refrigerator increases a pulse width of driving current by converting the conduction method of the motor to drive the motor at a low speed during power-saving operation of the refrigerator.

Abstract: The invention relates to an electric device (1) comprising an alternating current electric motor (3) and a control inverter (5) for controlling the phase or phases of the motor (3). The motor (3) comprises, on at least one winding of at least one phase (PA, PB, PC), a point (Ma, Mb, Mc) for measuring a voltage relative to a predefined potential (M), the measurement point (Ma, Mb, Mc) being chosen so that it divides the winding into a first (Za1; Zb1; Zc1) and a second (Za2; Zb2; Zc2) portion such that the electromotive forces (ea1, ea2) induced in the two portions are phase-shifted relative to one another and means (11A; 11B; 11C) for measuring the voltage between the measurement point and the predefined potential. The invention also relates to an associated method for measuring electromotive forces.

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 speed of the electric machine. Additionally, a control system for an electric machine, and a product incorporating the control system and electric machine.

Abstract: A runout measurement system is proposed for measuring the runout of a moving surface of a device having a rotating body, such as a mass storage device (100) (e.g. a hard disk drive) having a rotor which in use includes a rotating recording medium. A sensor (102) interacting with the moving surface obtains a displacement signal. The displacement signal is sampled by a sampling unit (104) controlled by a unit (109) which initiates sampling based on both a signal indicating a ZCP and the clock signal of a high frequency (e.g. 20 MHz) clock (106). Simultaneously, the same clock (106) is used by a counter 108 to measure the spacing between one or more ZCP times. This permits the correspondence between the sampling times and the angular position of the rotor to be found with a high accuracy which depends upon the clock frequency, and thereby allows calculation of repeatable runout (RRO) and non-repeatable runout (NRRO).

Abstract: A motor driving circuit includes an inverter circuit which supplies a driving current to a coil of a single phase brushless DC motor, a position detection sensor which detects a magnetic pole position of a magnet rotor of the motor and outputs a position detection signal, and a controller which controls the inverter circuit based on the position detection signal and a speed instruction signal for instructing a rotating speed of the motor. At a time of startup of the motor, the controller makes a pulse width of a PWM signal for controlling the inverter circuit constant in a first time period which starts after the position detection signal zero-crosses and lasts until the position detection signal zero-crosses next time, and narrows the pulse width of the PWM signal as time elapses in a second time period immediately after the first time period.

Abstract: An inverter control device of the present invention operates by synchronous commutation in which a commutation signal waveform is output with an electric angle of less than 180 degrees at a predetermined frequency according to a target rotation speed of a brushless DC motor. In order to maintain an induced voltage phase of a brushless DC motor at a predetermined phase with respect to an output voltage of an inverter circuit unit, even in an operation by the synchronous commutation, the output voltage of the inverter circuit unit is changed according to a change in state of the induced voltage phase of the brushless DC motor to continue a running state of the motor. Therefore, a more stable motor operation can be performed during synchronous running by the forced commutation.

Abstract: This invention provides a motor driving apparatus that made it possible to reduce torque ripples including those attributed to load variation of the motor and an associated method for control of motor revolution. An output stage to a multiphase DC motor is comprised of power elements to supply output voltages to multiphase coils and a predriver to supply drive voltages to the power elements. A resistor means detects a current flowing through the power elements. A supply current detector detects a voltage signal produced across the resistor means as a supply current, using a high-speed ADC and a moving average filter. An output controller generates a PWM signal with a frequency lower than the frequency of the high-speed ADC so that the current detected by the supply current detector conforms to a current signal indicating a motor revolving speed and transfers the PWM signal to the output stage.

Abstract: Sensorless driving of a brushless DC (BLDC) motor includes detecting a zero crossing time from back electromotive force (BEMF) voltage of the BLDC motor. An instantaneous BEMF voltage and an average BEMF voltage are compared to detect the crossover time, which can be used to change the commutation switching sequence. Since the average BEMF voltage differs for odd and even steps of the commutation switching sequence, average BEMF voltages are calculated separately for odd and even sequences and compared to instantaneous BEMF voltages to detect crossover points for the odd and even sequences. The times to commutations for the odd and even sequences are averaged to provide an average time to the next commutation cycle. The average time can be scaled by a reduction factor to reduce the effects of measurement noise.

Abstract: In a multi-phase brushless DC motor, a zero crossing N-bit filter includes a comparator and a phase multiplexer. The phase multiplexer connects each motor phase to each of a positive and a negative input of the comparator, with a switch in each connection to form a switch array. A microprocessor is disposed to operate the switches, and is configured to measure a BEMF for a first phase by opening the switches connecting all other phases to the positive input of the comparator and by opening the switch connecting the first phase being measured to the negative input of said comparator. The comparators output is received by a shift register. The microprocessor is configured to respond to a zero crossing when a majority of bits in the shift register change between high and low.

Abstract: The PWM control circuit includes a polarity determination unit, a full wave rectification unit, an adjustment unit that generates an adjusted waveform signal by adjusting waveform of the full wave rectification signal, and a carrier signal generating unit that generates a fixed frequency carrier signal. The PWM control circuit further includes a comparator that generates an original PWM signal by comparing the adjusted waveform signal and the carrier signal, and a PWM waveform shaping unit that generates a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, by shaping the original PWM signal according to the polarity signal.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes generating a first signal having a voltage that is proportional to a voltage across a winding of the motor, and generating a second signal having a voltage that is proportional to a current in the winding. The second signal is then differentiated to generate a third signal, and the voltages of the first signal and the third signal are compared. An output signal is generated in response to the comparison, the output signal having an edge whenever the voltages of the first signal and the third signal correspond. The winding is then commutated at times relative to the edges in the output signal. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A power converter for an electric rotating machine is provided which is designed to ensure a desired length of a current flywheel duration in which current is permitted to freewheel from the electric rotating machine even if the power converter is in a transient state or subjected to an unexpected change. The power converter is equipped with a controller and a switching circuit which is disposed between a power supply and windings of the electric rotating machine. The switching circuit has switches grouped into an upper and a lower arm. The controller works to control an off-operation of one of the switches of one of the upper and lower arm so as to produce a desired length of the current flywheel duration following turning off of the one of the switches, thereby minimizing a loss of rectification and avoiding the backflow of current from the power supply to the windings.

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.