Abstract: A control system for a motor includes an inverter coupled to the motor. The control system further includes a microcontroller coupled to the inverter. The microcontroller includes a processor programmed to measure an input voltage and acquire a back EMF voltage of the motor. The processor is also programmed to control the inverter to regulate the motor voltage based on the input voltage and the back EMF voltage to facilitate controlling the motor.

Abstract: A synchronous machine control apparatus for correcting a rotor position error that is a difference between a rotor position of a synchronous machine and a rotor position detected by a position detection unit is provided with a current control device for performing control in such a way that respective current command values and respective current detection values in a generation direction (? axis) of an armature interlinked magnetic flux and in a direction perpendicular (? axis) to the generation direction of the armature interlinked magnetic flux coincide with each other and with a magnetic flux calculation device for calculating a phase of an armature interlinked magnetic flux, based on an armature current detection value of the synchronous machine and an armature voltage command value therefor; the rotor position error is corrected based on the ??-axis current command values and a phase of the armature interlinked magnetic flux.

Abstract: Method and device for operating an asynchronous motor having increased efficiency. According to the invention, ranges for a motor size of the asynchronous motor are specified. In addition, a value of the motor size is calculated depending on at least one measurement value of a measurement parameter during the operation of the asynchronous motor, wherein the respective calculated value of the motor size is allocated to one of the ranges. Furthermore, a control parameter is changed depending on the range to which the calculated motor parameter is allocated to provide an optimised control parameter such that the control parameter is changed beginning from a starting value specified for the respective range of the motor size until a predetermined criterion for a specific motor size is reached. Furthermore, the optimised control parameter is stored as a support point of a continuous optimal characteristic curve for the control parameter depending on the range to which the calculated motor size is allocated.

Abstract: A control apparatus for an AC rotary machine includes a control circuit, a power converter, a current detector, and a voltage detector. The control circuit includes: an activation current instruction unit which generates a current instruction for activation; and a start phase setting unit which sets an initial rotation phase for activation control, based on the rotation direction of the AC rotary machine just after activation and on the polarity of current detected by the current detector just after activation. Thus, the current amplitude and torque shock just after activation control is started can be reduced, and assured and stable reactivation is allowed without causing the protection operation.

Abstract: A magnetic force estimating unit (38) for estimating the magnetic force of a permanent magnet of a rotor of a motor (6), a determining unit (39), and a demagnetization responsive timing changing unit (40) are provided in an inverter device (22) or an electric control unit (21). The magnetic force estimating unit (38) performs a determination of the magnetic force with a predetermined rule from detection signals of at least two of the motor rotation number, motor voltage and motor current. The determining unit (39) determines whether or not a demagnetization occurs. In response to the result of determination by the determining unit (39), the demagnetization responsive timing changing unit (40) changes the timing, at which the maximum electric current relative to the phase of the rotor is fed, so that with respect the motor drive by the inverter device the reluctance torque of the motor may be increased.

Abstract: A pulse signal output unit sends three-phase pulse signals according to movement of the movable member. A counter unit adds a first predetermined value or a second predetermined value to a count value or subtracts the first predetermined value or the second predetermined value from the count value, according to a combination of the pulse signals appearing when all the pulse signals are normal and a combination of the pulse signals appearing when one of the pulse signals malfunctions. A position detection unit detects the position of the movable member according to the count value.

Abstract: A controller 40 performs a control operation in a cycle based on a carrier frequency fc of a carrier, specifically, at timings corresponding to the peaks and troughs of the carrier signal. Moreover, in the case where the carrier frequency fc is switched, a disturbance estimation part forming the controller 40 updates control constants that are used for disturbance estimation and are dependent on the control operation cycle, in a control operation performed one cycle after a control operation immediately after the switching of the carrier frequency fc.

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: A control apparatus for an AC rotating machine that can reliably and stably start up an AC rotating machine, particularly a synchronous motor using a permanent magnet, in position-sensorless vector control thereof, includes: a steady speed calculator that calculates, during steady state control of the AC rotating machine, a rotation angular frequency of the AC rotating machine based on an AC current and voltage commands; and a start-up speed calculator that calculates, during start-up control within a predetermined period after the AC rotating machine has been started up, the rotation angular frequency of the AC rotating machine based on the AC current and the voltage commands. The control apparatus corrects during the start-up control current commands so that the AC voltage amplitude of the voltage commands will be a constant value not more than the maximum output voltage of a power converter.

Abstract: A vehicle includes a polyphase, permanent magnet synchronous electric machine, DC and AC buses, a battery module, a traction power inverter module (TPIM), and a controller. The controller, which is in communication with the TPIM, executes a method to detect a fault condition, fixes the pulse width modulation (PWM) duty cycles of all phases of the electric machine to 50% such that all phases switch simultaneously, and applies a polyphase OPEN state to the AC bus in response to the detected fault condition. The controller then transitions to a polyphase SHORT state by automatically inserting an adjustable deadtime at each PWM switching transition of the TPIM over a calculated ramp duration, thereby transitioning from an initial deadtime to a minimum deadtime over the calculated ramp duration. The transition reduces peak overshoot of the negative d-axis current of the machine during the fault condition.

Abstract: A method for testing rotation speed of a fan receives a duty cycle ratio related to the fan sent from a dial switch on a test board connected to the fan. The method transmits a pulse width modulation (PWM) signal based on the duty cycle to the fan to power rotation of the fan, then detects the PWM signal transmitted to the fan and a tachometer (TACH) signal transmitted from the fan. The method gathers the duty cycle ratio related to the fan from the PWM signal and an actual rotation speed of the fan from the TACH signal, and displays the duty cycle ratio and the actual rotation speed together on the test board.

Abstract: A driving circuit for a single-phase-brushless motor and a method that includes a driving-signal-generating circuit configured to generate a driving signal for supplying, to a driving coil of the single-phase brushless motor, an output circuit coupled to the driving signal generating circuit; and an induced voltage zero-cross detecting circuit having a plurality of inputs and an output, a first input coupled to the driving signal generating circuit and configured to detect a zero cross of an induced voltage in response to operation in the de-energized period.

Abstract: The invention relates to a drive device and a drive method for a brushless motor. In a drive method in which a switching timing of energization patterns is detected by comparing a pulse induced voltage of a non-energized phase with a voltage threshold, when the pulse induced voltage does not reach the voltage threshold, the pulse induced voltage at an angle of switching the energization patterns is measured. Discrimination between a demagnetization failure and a lock failure is performed based on whether the measured pulse induced voltage satisfies a predetermined condition or not. When it is the demagnetization failure, motor control continues after changing the voltage threshold. When it is the lock failure, the motor control stops.

Abstract: The present invention is directed to a method of estimating a motor rotation angle that does not affect precision of a detected angle of a crank angle sensor, which is an alternative sensor, when abnormality occurs in a resolver and a peripheral circuit, and performing a motor control without failure of an inverter or peripheral device. A vehicle system includes a motor, a resolver detecting a rotor rotation angle of the motor, a motor control circuit controlling the motor based on information on rotor rotation angle and torque command value, an engine connected to the motor through a crankshaft, and a crankshaft sensor detecting revolutions of the crankshaft, in which the motor control circuit estimates rotor rotation angle based on a variation rate of the number of revolutions of the crankshaft when abnormality of the resolver is detected, and performs a weak field control based on estimated rotor rotation angle.

Abstract: The invention relates to a brushless motor drive device that performs switching determination of energization modes of a three-phase brushless motor according to a sensorless method, and a drive method thereof. A pulse induced voltage induced in a non-energized phase of three phases by a pulse voltage is compared with a threshold to determine the switching timing of the energization modes. Here, by limiting a duty ratio of a voltage application to equal to or greater than a lower limit, a situation in which the pulse induced voltage is sampled while the pulse induced voltage is oscillating is avoided, and a situation in which the pulse induced voltage falls below a voltage detection resolution is avoided. As a result, determination of energization mode switching timing based on a pulse induced voltage can be performed more stably.

Abstract: In a method and a device for identifying a reversing operation in an electric actuating unit of a vehicle, once a trapped object is detected, the rotational direction of the electromotive drive is commutated. Sequential pulse interval counter values, derived from a sensor system or data derived from the values is or are written to a ring buffer store and compared with pre-defined reference data patterns. If a match is found, the counter reading of the position counter is corrected in accordance with the pre-defined reference data pattern. This ensures that the counter reading of the position counter is correct even after a reversing operation.

Abstract: The inventive concept provides a motor driving module, a operating method for the same, and a Brush less Direct Current (BLDC) motor system. The motor driving module is provided which comprises a motor driving unit configured to output a plurality of switching signals based on a plurality of position signals and a control signal; and a Pulse Width Modulation (PWM) inverter configured to output 3-phase voltages based on the plurality of switching signals outputted from the motor driving unit, wherein the motor driving unit comprises; a correction circuit configured to detect an error of the plurality of position signals to output a compensation signal based on the detecting result; and a control circuit configured to output the plurality of switching signals based on the compensation signal and the control signal, wherein the plurality of position signals indicate a position of a rotor in an external motor.

Abstract: There are a motor driving control apparatus and method, and a motor using the same, the motor driving control apparatus including a back-electromotive force detecting unit detecting back-electromotive force generated from a motor apparatus, an offset correcting unit determining whether an offset delay is present in the back-electromotive force detecting unit and correcting the offset delay when the offset delay is present, and a controlling unit controlling a driving of the motor apparatus using the back-electromotive force in which the offset delay is corrected by the offset correcting unit.

Abstract: Automotive propulsion systems and methods of operation are provided. The automotive propulsion system includes a first voltage source, a power electronics device comprising a plurality of power switching devices coupled to the first voltage source, an electric motor having a plurality of windings coupled to the plurality of power switching devices and a neutral node interconnecting the plurality of windings, and a second voltage source coupled to the neutral node of the electric motor and the first voltage source.

Abstract: There are provided an apparatus and a method for controlling a motor. The apparatus for controlling a motor includes a signal generation unit generating a first signal indicating position information of a rotor, a counter unit sampling the first signal with a second signal different from the first signal for one period to count a sampling frequency, a memory unit storing a section counter value and an error value obtained by sampling a period immediately prior to the first signal with the second signal, and a comparison unit increasing and reducing an output signal when the sampling frequency counted by the counter unit coincides with the section counter value, wherein the comparison unit sums the sampling frequencies corresponding to error values with the sampling frequency of the first signal before the counter unit ends the sampling of one period of the first signal.

Abstract: A control device stores, as a dead time Td, a period from a point of time of a switching-off operation of an inverter to a point of time when an inverter output voltage becomes lower than a control target value “0”. In overmodulation PWM control over the inverter, the control device performs the switching-off operation at a time t1, and thereafter starts a switching-on operation at a time t2 with passage of dead time Td read from a memory. With the setting of dead time Td, the inverter output voltage becomes lower than the control target value “0” at time t2 at which the switching-off operation is started. Hence, the inverter output voltage just after the switching-on operation is less likely to be affected by surge voltage during the switching-off operation, whereby the peak value of the inverter output voltage is made small.

Abstract: A DC voltage value from a DC voltage detection section is input directly to a voltage correction section without passing through a compensator or a filter. Therefore, even when rapid voltage change occurs, such as short power interruptions, instantaneous voltage drop and return from instantaneous voltage drop, the voltage correction section can quickly perform the correction operation in response to the rapid voltage change. Since the amount of link resonance compensation is limited by the limitation section to a certain range, it is possible to prevent the amount of link resonance compensation from fluctuating excessively upon rapid voltage change. Since the amount of link resonance compensation which is limited by the limitation section to a certain range is input to one compensator that has an appropriate control band, among all control calculation sections, the response does not have to be unnecessarily fast, thus realizing a stable control.

Abstract: Disclosed herein are a motor control apparatus, an image forming apparatus, an image forming apparatus including the same, and a motor control method, by which position error of a motor and a control value for compensating for the position error are calculated and reflected in feedback control, thereby quickly removing position error of the motor.

Abstract: A motor control apparatus includes a phase sensing circuit, a current sensing circuit, a controller and a driving circuit. The driving circuit receives a first driving signal and then controls a phase switching state of the magnetic pole of the motor so as to drive the motor in accordance with the first driving signal. The phase sensing circuit detects the phase switching state of the magnetic pole to generate and output a phase switching signal to the controller during the motor is operating. The current sensing circuit detects a current flowing through the motor to generate and output a current phase signal to the controller. The controller compares a phase difference between the phase switching signal and the current phase signal to generate and output a second driving signal to the driving circuit. The driving circuit controls the phase switching state of the magnetic pole for driving the motor in accordance with the second driving signal.

Abstract: A system and a motor controller for a motor vehicle, the motor controller having electronics configured to bring about the energization of the windings of an electric motor. A clock generator is configured to send a clock signal which controls the processes of the electronics. The motor controller is operatively connected to a slave of a bus system in order to transmit and/or receive signals, and the clock of a clock signal being provided by the bus master is used via the slave to synchronize the clock generated by the clock generator of the motor controller.

Abstract: There are provided a circuit and a method for detecting a duty ratio of a PWM signal. The circuit includes: a counting unit counting a PWM signal; a detection indication determining unit determining whether a detection indication signal indicating a start of detection of the duty ratio of the PWM signal has been input; an edge detecting unit detecting a preset PWM edge of the PWM signal; and a duty calculating unit calculating the duty ratio of the PWM signal using a count value during a section from a k-th point in time (T(k)) (k being a natural number of 1 or more) at which the PWM edge is detected after it is determined that the detection indication signal has been input to a k+1-th point in time (T(k+1)) at which the PWM edge is detected after it is subsequently determined that the detection indication signal has been input.

Abstract: There is provided a motor driving apparatus capable of stably performing operation conversion between a normal mode and a sleep mode by counting a duty of the PWM signal according to a preset clock signal, the motor driving apparatus including: a pulse width modulation (PWM) signal generating unit providing a PWM signal for driving a motor; a driving unit operating normally in a normal mode and waiting for operation in a sleep mode according to a control, and driving the motor in response to the PWM signal of the PWM signal generating unit; and a driving controlling unit counting a duty of the PWM signal according to a preset clock signal to determine an operation mode of the driving unit.

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 motor driving device comprises: an inverter having a plurality of switching elements for driving a motor; an arithmetic section for calculating a rotational speed and a magnetic pole electric angle of a motor rotor based on information about a motor phase voltage and information about a motor phase current; a delay correcting section for correcting a phase delay of the magnetic pole electric angle calculated by the arithmetic section so as to generate corrected magnetic pole electric angle; a driving command generating section for generating a sinusoidal wave driving command based on a difference between the rotational speed and a target rotational speed and the corrected magnetic pole electric angle; and a PWM signal generating section for generating a PWM control signal for controlling on/off of the plurality of switching elements based on the sinusoidal wave driving command.

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 first calculation unit subtracts third digital data which indicates the minimum value of the duty ratio from first digital data which indicates the duty ratio of the PWM driving operation. A slope calculation unit generates slope data which is dependent on the temperature based upon second digital data which indicates the temperature. A second calculation unit multiplies the slope data by the output data of the first calculation unit. A third calculation unit sums the output data of the second calculation unit and the third digital data. A selector receives the output data of the third calculation unit and the third digital data, selects one data that corresponds to the sign of the output data of the first calculation unit, and outputs the data thus selected as a duty ratio control signal.

Abstract: There are provided a motor driving apparatus and a motor driving method capable of decreasing power consumption by readjusting a preset duty ratio according to a voltage level of driving power. The motor driving apparatus includes: a driving power detecting unit detecting a voltage level of driving power used to drive a motor; a speed controlling unit adjusting a preset duty ratio of a pulse width modulation (PWM) signal when the voltage level detected by the driving power detecting unit is equal to or less than a preset reference voltage; a driving controlling unit generating a driving signal having the duty ratio from the speed controlling unit; and a driving unit driving the motor according to the driving signal of the driving controlling unit.

Abstract: A controller for a brushless motor that includes an input for receiving an analog signal, an analog-to-digital converter (ADC) for sampling the analog signal, and a processor. The processor starts the ADC during a first electrical half-cycle and reads the ADC during a second electrical half-cycle of the motor. Additionally, a motor system that includes the controller.

Abstract: A vehicle, including a motor having a rotor, a resolver that detects a rotation angle of the rotor and a control device, and a control method for the vehicle are provided. The control device executes rectangular-wave control over the motor using the rotation angle of the rotor, detected by the resolver, executes zero learning for learning a deviation between an origin of an actual rotation angle of the rotor and an origin of the detected rotation angle of the rotor, corrects the detected rotation angle of the rotor on the basis of a result of the zero learning, and, when the zero learning has not been completed yet, executes avoidance control for avoiding a rapid variation in output of the motor.

Abstract: To present a motor drive control device capable of realizing high speed driving by a simple power feeding control method. The motor drive control device of the invention has a three-phase full bridge circuit for adjusting the feeding phase so as to invert the terminal voltage in feeding-off time, by cyclically repeating positive direction feeding period, non-feeding period, negative direction feeding period, and non-feeding period. In high speed driving, the phase is adjusted so as to invert the terminal voltage right after feeding-off, and if not reaching the desired rotating speed, the feeding time is shortened. As a result, the phase angle to the actual applied voltage can be advanced, and high seed rotation by weak-field system driving is realized.

Abstract: A motor control system includes a power supply to supply current to a motor, a shunt resistor provided at one side of the motor to measure the magnitude of current supplied to the motor, a differential amplifier to receive a voltage applied to both ends of the shunt resistor as an input signal and amplify the input signal, an Analog/Digital Converter (ADC) to convert an analog signal generated from the differential amplifier into a digital signal, a switch to switch current applied to the motor by the power supply, and a microcontroller to generate a Pulse Width Modulation (PWM) control signal so as to control ON or OFF of the switch and generate an operation start signal of the ADC by considering the PWM control signal and a hardware delay value of the differential amplifier.

Abstract: The present invention provides a semiconductor device, an electrical device, and a control signal generation method that enable easy generation of a given control signal even by a comparatively low cost and low processing power microcontroller. Namely, a microcontroller of a motor control system includes a PWM device equipped with a PWM setting register. The PWM setting register includes a duty update cycle register, a duty update value register and a duty update-times number register. A PWM generator generates and outputs a PWM signal according to values set in each register of the PWM setting register. The PWM device is capable of generating and outputting a PWM signal automatically with the PWM generator according to setting values set in the PWM setting register, even without an interruption by the software (CPU).

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: A method of controlling a brushless motor that includes exciting a winding of the motor for a conduction period over each electrical half-cycle of the motor. The length of the conduction period is defined by a waveform that varies periodically with time. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: Motor control circuits and associated methods to control an electric motor provide an ability to synchronize a rotational speed of the electric motor with an external clock signal, resulting in reduced jitter in the rotational speed of the electric motor.

Abstract: A control method for a sensor-less, brushless, three-phase DC motor. The effects of commutation on the motor may be minimized using a sinusoidal current drive on each electromagnet. The “off” times and/or the “on” times of the drive transistors controlling the electromagnets in a full “H-bridge” configuration drive scheme may be delayed. By overlapping the drive signals to the electromagnets with respect to a commutation command, the effects of switching between electromagnets may be minimized. In addition, the “on” and “off” times may also be adjusted during the overlapping to further ensure that the coils continuously conduct current, and that the current does not change direction during the switching. The delays, and hence the overlap times of the coil drive signals may be dynamically controlled, for example by using digital timers, making the response predictable and easily controlled.

Abstract: A PI calculation unit of a rectangular-wave voltage control unit calculates a control deviation by performing a PI calculation on a torque deviation relative to a torque command value, and outputs a voltage phase of a rectangular-wave voltage in accordance with the control deviation. A rate-of-change limiter imposes a restriction on the rate of change of the voltage phase. Here, the rate-of-change limiter lessens the restriction on the rate of change of the voltage phase, when the rate of change of the rotational speed of an electric motor is larger than a predetermined value representing an abrupt change of the rotational speed of the electric motor.

Abstract: An inverter includes a voltage command generator generating a voltage command value according to an externally specified voltage value, a PWM signal generator generating a PWM signal according to the voltage command value and frequency command value, and a switching unit generating a three-phase AC power according to the PWM signal. The voltage command generator decreases the voltage command value if the output current increases, to prevent the rotation speed of a prime move from suddenly changing. If the output current exceeds a preset upper current threshold, the voltage command value is clamped at a preset minimum output voltage, thereby securing the minimum output voltage for an increase in the output current.

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: A microcomputer that outputs a pulse signal controlling an ultrasonic motor includes a digital/analog, D/A, conversion set register that stores a D/A conversion set value setting an amplitude value of the pulse signal, a D/A converter that generates the amplitude value based on the D/A conversion set value, a first compare register that stores a first compare register value setting a frequency of the pulse signal, a second compare register that stores a second compare register value setting a duty ratio of the pulse signal, a counter that outputs a count value, a first comparator that compares the first compare register value with the count value to generate a first comparison result signal, and a second comparator that compares the second compare register value with the count value to generate a second comparison result signal.

Abstract: A brushless motor drive circuit has a first AD converter which converts a voltage value depending upon a power supply voltage supplied from a power supply to drive a three-phase brushless motor, to a digital signal and outputs the digital signal. The brushless motor drive circuit has an energization timing adjustment circuit which outputs an adjustment signal for adjusting a lead angle value or a lag angle value of energization timing of the three-phase brushless motor, in response to the digital signal which is output by the first AD converter. The brushless motor drive circuit has an energization timing setting circuit which sets the energization timing of the three-phase brushless motor.

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 drive circuit includes: a drive circuit configured to drive a motor whose coil current decreases with increase in counter electromotive voltage of a motor coil; a detection circuit configured to detect whether or not a current value of the coil current is greater than a predetermined value; a first control circuit configured to control the drive circuit so that the current value of the coil current becomes smaller than or equal to the predetermined value, when it is detected that the current value of the coil current is greater than the predetermined value; and a second control circuit configured to control the first control circuit so that the first control circuit does not control the drive circuit based on a detection result of the detection circuit until a predetermined time has elapsed from a start of supply of the coil current.

Abstract: An electric power tool is provided with a three-phase brushless motor that drives a tool and a motor driver that drives the three-phase brushless motor with square voltage waves. The motor driver is able to set a conduction angle to a value that is equal to or more than 130 degrees but not more than 180 degrees, and especially to change the conduction angle among at least two values that are equal to or more than 130 degrees but not more than 180 degrees. In this configuration, it may be preferable that the conduction angle is set to a larger value as a load applied to the tool becomes smaller. On the other hand, it may be also preferable that the conduction angle is set to a larger value as a load applied to the tool becomes smaller.

Abstract: A power tool includes a housing, a brushless DC motor housed inside the housing, a power supply, a control unit, and an input unit such as a trigger switch actuated by a user. The control unit controls the commutation of the motor through a series of power switches coupled to the power supply. The control unit initiates electronic braking of the motor after occurrence of a condition in the input unit, such as trigger release or reduced speed, indicative of the power tool shut-down. A mechanism is provided to power the control unit for a predetermined amount of time after the detection of the condition from the input unit in order to complete the electronic braking of the motor.