Abstract: A control device (2) for controlling power supply to a continuous-rotation motor, of the horological, DC type, is arranged to generate electrical pulses with a lower supply voltage to drive the rotor. The number of pulses per time interval is a function of the load applied to the motor. A voltage divider is arranged to supply the lower supply voltage with a plurality of different values and thus the electrical pulses with a variable voltage. A logic circuit counts the numbers of electrical pulses in successive time periods; to periodically select a voltage value, from among a plurality of different values, as a function of a counted number of electrical pulses or of a succession of counted numbers of electrical pulses; and to control the voltage divider so that the latter supplies the lower supply voltage with the selected voltage value after the selection of this voltage value.

Abstract: The present disclosure relates to a motor driver and a method of driving a motor capable of driving a motor with optimum efficiency. The method of driving the brushless direct current (BLDC) motor may include an initial driving operation, a test operation of adjusting a turn-on time and a transition time in the test mode step by step, driving the BLDC motor by applying the adjusted turn-on time and the adjusted transition time, and detecting a driving error of the BLDC motor, an operation of repeating the test operation when the driving error is not detected in the test operation, and an operation of setting the turn-on time and the transition time, which are adjusted in an operation just before the driving error is detected, as a turn-on time and a transition time in an optimum driving mode.

Abstract: A motor drive device enabling efficient position control at a low cost is provided. The motor drive device includes a position detection unit configured to detect a current position of an object to be driven by a motor and a motor control unit configured to calculate an output control amount for the motor based on a deviation between the current position and a target position of the object to be driven by the motor while changing an advance angle in a rotational phase of the motor according to the output control amount when the advance angle is within a predetermined advance angle range in the rotational phase of the motor and changing a drive voltage of the motor with the advance angle fixed when the advance angle is outside the predetermined advance angle range.

Abstract: A motor control apparatus includes: a motor drive control section that controls driving of a motor using a predetermined phase; a rotation position detecting section that, at every 180 degrees of an electrical angle of the motor, outputs two kinds of detection signals according to the rotation position of the rotor of the motor; a stopped position estimating section that estimates the stopped position at the start of rotation of the rotor using an elapsed time from when rotation the rotor starts until the kind of the detection signal outputted from the rotation position detecting section switches; a rotational speed estimating section that estimates the rotational speed of the rotor using the elapsed time and the stopped position; and an estimated phase calculating section that calculates an estimated phase as the aforementioned predetermined phase using the rotational speed.

Abstract: A gaseous-fluid environmental sensor having a gaseous-fluid flow system that defines a flow path coupling an intake port to an exhaust port. The gaseous-fluid flow system includes a blower and a flow sensor. The blower includes a motor and the flow sensor is for sensing a flow parameter. The gaseous-fluid environmental sensor further includes a controller electrically coupled to the flow sensor and the motor. The controller is configured to drive the motor with a first commutation sequence and to drive the motor with a second commutation sequence different than the first commutation sequence. The controller is further configured to select the first commutation sequence and the second commutation sequence based on the sensed flow parameter. Also discloses is a method for controlling the gaseous-fluid environmental sensor.

Abstract: A method for magnetic/impedance burst testing of large electric motors to determine broken rotor bar defect. The method providing a portable tester and includes a Signal Processor, a single-phase power source VAC, an AC/DC boost converter connected to the power source, at least one energy storage device connected to the AC to DC boost converter, a Pulse Width Modulated drive module (PWM) connected to the at least one energy storage device, and a series of at least three switches (IPM) using switch/level boost-type PWM rectification. The burst test is repeated until a full rotation of magnetic angles are tested and recorded with the Signal Processor. Rotor impedance versus magnetic angle of the full rotation is verified in order to check for failure, and broken rotor bar defect is determined when a shift in measured stator's impedance/admittance level for any of the given magnetic angles is identified by the Signal Processor.

Abstract: To solve the problem of multi-pulse control in which the load of the control software is increased and further switching/timing adjustment is required, a semiconductor device includes a control unit including a CPU and a memory, a PWM output circuit for controlling the driver IC to drive the power semiconductor device, a current detection circuit for detecting the motor current, and an angle detection circuit for detecting the angle of the motor. The PWM output circuit includes a square wave generator circuit to generate a square wave based on the angle of the angle detection circuit as well as the base square wave information.

Abstract: According to at least some embodiments, a method for driving a motor includes, upon a restart of the motor, determining whether the rotor is rotating based on a signal generated from outputs of at most one Hall sensor. The method further includes, if it is determined that the rotor is rotating, determining a plurality of output duty values for driving a plurality of windings of the motor. The method further includes generating a drive signal for driving the motor based on the determined plurality of output duty values.

Abstract: A method for determining an updated rotor speed for a motor is provided. The method obtains, by a processor, a current rotor speed of the motor; determines a current mode for the motor, based on the current rotor speed, wherein the current mode comprises a low-speed mode, an intermediate speed mode, or a high-speed mode; detects one or more Hall events associated with a plurality of digital Hall Effect sensors coupled to the motor, based on the current mode; calculates, by the processor, a new rotor speed for the motor, based on the one or more Hall events and the current mode; and transmits the new rotor speed as a motor speed feedback signal, for digital speed control of the motor.

Abstract: In accordance with an embodiment, a sensor-less detection circuit is provided that includes a first voltage adjustment circuit coupled for receiving an induced voltage and a second voltage adjustment circuit coupled for receiving a common voltage. A differential amplifier has an inverting input terminal coupled to the first voltage adjustment circuit and a noninverting input terminal coupled to the second voltage adjustment circuit. In accordance with another embodiment, a method for detecting a motor rotor position is provided that includes receiving a first back electromotive force that is at a first voltage level and shifting the first back electromotive force from the first voltage level to a second voltage level. The first back electromotive force is filtered to generate a first filtered voltage; and a first motor rotor position signal is generated in response to comparing the first filtered voltage with a reference voltage.

Abstract: In accordance with an embodiment, a sensor-less detection circuit is provided that includes a first voltage adjustment circuit coupled for receiving an induced voltage and a second voltage adjustment circuit coupled for receiving a common voltage. A differential amplifier has an inverting input terminal coupled to the first voltage adjustment circuit and a noninverting input terminal coupled to the second voltage adjustment circuit. In accordance with another embodiment, a method for detecting a motor rotor position is provided that includes receiving a first back electromotive force that is at a first voltage level and shifting the first back electromotive force from the first voltage level to a second voltage level. The first back electromotive force is filtered to generate a first filtered voltage; and a first motor rotor position signal is generated in response to comparing the first filtered voltage with a reference voltage.

Abstract: Provided are a detecting unit that detects that a light-shielding member has passed a predetermined position at the time of the light-shielding member moving to a closed state and to an opened state, and a control unit that changes at least one of a driving start timing at the time of driving a stepping motor and a driving speed at the time of driving the stepping motor, based on the detection results of the detecting unit.

Abstract: A rotating electric machine is applied to a multilayer winding-type rotating electric machine including a stator and a rotor. The stator includes an armature winding. The rotor includes at least one of a field winding and a permanent magnet for generating a magnetic field that have characteristics of magnetic flux of a non-sinusoidal waveform in relation to a rotation angle of the rotor. The armature winding has winding groups. Each of the winding groups has coils that are connected to an actual neutral point provided for each winding group, and has a first winding group and a second winding group that have a phase difference. A control apparatus detects a rotation angle based on a voltage at the actual neutral point of the first winding group and a voltage at the actual neutral point of the second winding group, and controls the rotating electric machine based on the rotation angle.

Abstract: A multi-phase electric motor is proposed that comprises a rotor and a stator. The rotor has a number of magnets directed towards the stator and the stator includes a plurality of phase windings directed towards the magnets. The phase windings are connected to control units that are adapted to selectively apply a current to the phase windings to induce an electromagnetic force which acts upon the magnets to effect a rotation of the rotor. The motor comprises at least two control units, each being configured to control the supply of current to three phase windings such that a different phase current is supplied to each of the three phase windings with a phase shift between said different phase currents being 120°, and wherein no two control units utilize the same current phase.

Abstract: An embodiment method for motor control includes monitoring a plurality of position sensors coupled to a revolving motor. The monitoring includes measuring transition times of respective output patterns produced by the position sensors, the respective output patterns each including at least one transition time that repeats in accordance with each revolution of the motor. The method further includes determining a first revolution period in accordance with the measured transition times. The method also includes determining an elapsed fraction of the first revolution period that has elapsed since a start time of the first revolution period.

Abstract: Intermediate connecting devices and electronically commutated (ECM) motors for HVAC systems are disclosed, as well as methods for their use within the HVAC systems. An interface component device coupled to a system controller and an ECM motor may be configured to receive a first and second signal, and convert the voltage across the received signals to a lower-value voltage signal compatible with the ECM motor. The converted voltage signal may be transmitted to the ECM motor to cause the motor to operate in one of a plurality of operation modes. An ECM motor that includes a tap detection circuit and a processor may be configured to receive a voltage signal from the interface component and detect at which input port the voltage signal is received. The ECM motor may select the operation mode for the motor based on the detection of which input port received the voltage signal.

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 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: Various examples are provided for brushless direct current (DC) motor control over a wide dynamic range. In one example, among others, a system including a power drive coupled to a DC motor and a MCU configured to control commutation of the DC motor based upon shaft speed of the DC motor, where the MCU transitions between a motion-based commutation mode and a time-based commutation mode in response to a comparison of the shaft speed with a predefined threshold. In another example, a method includes commutating a DC motor in response to a transition in rotor position of the DC motor and transitioning from a motion-based commutation mode to a time-based commutation mode in response to a comparison of shaft speed of the DC motor to a predefined threshold.

Abstract: An apparatus for determining the position of the rotor of an electric machine in relation to the stator, wherein the electric machine has at least three winding phases, which each have at least one pole winding with a magnetizable core, with devices for detecting a measurement signal. The instantaneous degrees of magnetization of the pole winding cores influenced by the magnetic field of the rotor, depend on the position of the rotor. The devices for detecting the measurement signal for tapping off the measurement signal are provided exclusively outside the electric machine at connecting conductors used for energizing the electric machine. Preferably, switching devices for temporarily isolating at least one of the connecting conductors from an operating voltage source are provided, wherein the measurement signal can be tapped off at the connecting conductor which has been isolated from the operating voltage source.

Abstract: A motor drive control apparatus for performing motor control that is stable and has a good efficiency includes: a speed processing unit that generates a first value by converting a second value corresponding to a current speed into a duty ratio; a torque processing unit that generates a third value by converting a fourth value corresponding to a target torque into the duty ratio; and a drive unit that controls switching by a switch included in a complementary switching amplifier by an average duty ratio corresponding to a sum of the first value and the third value to drive a motor connected to the complementary switching amplifier.

Abstract: A method for controlling an inverter in a system including a load, a motor for driving the load, and an inverter for operating the motor comprises when a load amount of the load is reduced to below a sleep level, checking whether a time corresponding to a sleep delay has lapsed; when the load amount of the load is still below the sleep level even after the sleep delay, varying an operating frequency of the motor, and if there is no change in a feedback from the load in response to the variation in the operating frequency, controlling the inverter to enter a sleep mode.

Abstract: A circuit for filtering narrow pulse and compensating wide pulse, including a signal shaping circuit, a filter circuit, and a pulse width compensating circuit. The signal shaping circuit processes an input signal and transmits the input signal to the filter circuit. The filter circuit filters off narrow pulses of the input signal. The pulse width compensating circuit compensates the wide pulses of the input signal and outputs an output signal.

Abstract: A method of controlling a brushless motor that includes rectifying an alternating voltage to provide a rectified voltage having a ripple of at least 50%, exciting a winding of the motor with the rectified voltage, and performing a first process or a second process in response to current in the winding exceeding a threshold that is proportional to the rectified voltage. The first process includes freewheeling the winding, while the second process includes continuing to excite the winding for an overrun period and freewheeling the winding at the end of the overrun period. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: Provided is an apparatus for controlling speed in induction motor in which tension command and friction loss compensation are used to calculate a torque limit relative to an output of a speed controller, which is then used to limit the speed of the induction motor, whereby a tension sensor and a position sensor are not used in the continuous processing line to improve performance of the vector control type induction motor.

Abstract: An air conditioner includes: an outdoor fan provided in an outdoor unit; a permanent magnet synchronous motor that drives the outdoor fan; an inverter that uses a DC power source as a power source and applies a voltage to the permanent magnet synchronous motor; an inverter control means that controls the output voltage of the inverter; and a shunt resist connected between the DC power source and the inverter. If the outdoor fan is rotating due to an external force while the inverter is stopped, the inverter control means causes the inverter to operate using a brake sequence that brakes the rotation of the outdoor fan, and then causes the inverter to operate using a drive sequence that power-drives the outdoor fan.

Abstract: In various implementations, a condition of a motor may be monitored based at least partially on time required to achieve a change in speed. A notification may be transmitted based on the condition of the motor.

Abstract: A motor control device and a motor control method are disclosed herein, where the motor control device includes a signal conversion unit, a frequency multiplication unit, a profile generation circuit and a frequency converter unit. The signal conversion unit receives a rotation speed signal from a motor and converts the rotation speed signal into a digital signal. The frequency multiplication unit generates a frequency multiplication signal based on the digital signal. The profile generation circuit performs frequency division on the frequency multiplication signal to get a profile signal. The frequency converter unit generates a reference signal and compares the reference signal with the profile signal to output a motor control signal.

Abstract: Proposed is a driver having dead-time compensation function. The driver having dead-time compensation function generates an output voltage according to a voltage command and a frequency command. The driver includes an inverter, an output current detector and a control unit. The inverter receives a DC voltage and operates with a pulse width modulation mode so that the driver outputs the output voltage and an output current. The output current detector detects the current value of the output current to generate a output current detecting signal. The control unit outputs a switching control signal to inverter according to the voltage command and the frequency command. The control unit corrects a reference command according to dead-time and the output current detecting signal related to the output current so that amplitude and waveform smoothness of the output voltage and the output current are compensated.

Abstract: An inverter and a control unit that has a command signal processing unit and a PWM frequency control unit and performs pulse width modulation control are provided. If the command signal processing unit has received a first PWM frequency command signal, it outputs a low PWM frequency command signal so that synchronous or asynchronous PWM control is performed at a PWM frequency in a predetermined frequency range. The command signal processing unit outputs a high PWM frequency command signal so that synchronous or asynchronous PWM control is performed at a higher frequency than the above-mentioned frequency if the command signal processing unit has received a second PWM frequency command signal and until a predetermined time period elapses. The command signal processing unit outputs a low PWM frequency command signal if it has received the second PWM frequency command signal and after the predetermined time period elapsed.

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 system and method for controlling an alternating current (AC) motor using a Field Programmable Gate Array (FPGA) to read the current and position measurements in an the AC motor, perform digital filtering of the position and current data, provide very precise synchronization of the measured phase current and position data, and output the data to a phase converter for control of the AC motor.

Abstract: A driving control device of a motor includes: a motor driving unit, which drives a motor in response to a driving control signal; and a control unit, which determines an energization pattern applied to an armature coil based on a detected rotational position of the rotor, wherein the control unit starts rotation control by a preset first energization pattern when activating of the motor, wherein when a predetermined time period has elapsed, the control unit adjusts energizing timing to be a timing, at which a short of each phase is not caused at switching of the energization pattern, and then outputs the driving control signal to the motor driving unit so that the rotation control is switched to rotation control of a second energization pattern, which has a predetermined advanced angle amount with respect to the first energization pattern.

Abstract: Systems and methods for estimating an inertia and a friction coefficient for a controlled mechanical system are provided. In one or more embodiments, an inertia estimator can generate a torque command signal that varies continuously over time during a testing sequence. The velocity of a motion system in response to the time-varying torque command signal is measured and recorded during the testing sequence. The inertia estimator then estimates the inertia and/or the friction coefficient of the motion system based on the torque command data sent to the motion system and the measured velocity data. In some embodiments, the inertia estimator estimates the inertia and the friction coefficient based on integrals of the torque command data and the velocity data.

Abstract: A ventilating system that can make an air flow rate variable includes a DC motor that drives blades and a control circuit that controls the DC motor. The control circuit includes a first current detecting unit that detects a current flowing in the DC motor, a rotating speed detecting unit that detects a rotating speed of the DC motor, and a control unit that controls the DC motor based on a rotating speed detected by the rotating speed detecting unit and a current detected by the first current detecting unit. The current detecting unit includes a plurality of low-resistance resistors, detects a motor current by using divided voltages of the low-resistance resistors, and calculates a ventilation air flow rate based on the rotating speed detected by the rotating speed detecting unit and the current detected by the first current detecting unit.

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 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 input circuit includes an interface structured to output a logic signal from an alternating current signal of a pair of elongated conductors. A load is switchable to the elongated conductors. A processor outputs a control signal to switch the load to the elongated conductors asynchronously with respect to the alternating current signal for a first predetermined time, inputs the logic signal, determines if the input logic signal is active a plurality of times during the first predetermined time and responsively sets a first state of the alternating current signal, and, otherwise, sets an opposite second state of the alternating current signal, and delays for a second predetermined time, which is longer than the first predetermined time, for the opposite second state before repeating the output, and, otherwise, delays for a third predetermined time, which is longer than the second predetermined time, for the first state before repeating the output.

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.

Abstract: A blower motor assembly having a variable speed motor that is suitable for replacing a PSC motor in a residential HVAC (heating, ventilation, and air conditioning) system. The blower motor assembly includes a variable speed motor and motor controller; a first power input for receiving a plurality of AC power signals from a control device for use in determining an operating parameter for the motor; and a second power input for receiving AC power from an AC power source for powering the motor controller even when no AC power signals are received by the first power input.

Abstract: A method for controlling an inverter in a system including a load, a motor for driving the load, and an inverter for operating the motor comprises when a load amount of the load is reduced to below a sleep level, checking whether a time corresponding to a sleep delay has lapsed; when the load amount of the load is still below the sleep level even after the sleep delay, varying an operating frequency of the motor, and if there is no change in a feedback from the load in response to the variation in the operating frequency, controlling the inverter to enter a sleep mode.

Abstract: An inverter and a control unit that has a command signal processing unit and a PWM frequency control unit and performs pulse width modulation control are provided. If the command signal processing unit has received a first PWM frequency command signal, it outputs a low PWM frequency command signal so that synchronous or asynchronous PWM control is performed at a PWM frequency in a predetermined frequency range. The command signal processing unit outputs a high PWM frequency command signal so that synchronous or asynchronous PWM control is performed at a higher frequency than the above-mentioned frequency if the command signal processing unit has received a second PWM frequency command signal and until a predetermined time period elapses. The command signal processing unit outputs a low PWM frequency command signal if it has received the second PWM frequency command signal and after the predetermined time period elapsed.

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

Abstract: A method of braking a washing machine from an operational speed to a reduced non-zero speed is provided (as well as a washing machine incorporating the method) for a washing machine driven by one of a synchronous or asynchronous motor. Upon receipt of a speed reduction signal, the motor rotating magnetic fields are collapsed for a defined time period. After the defined time period, DC braking voltage is applied to the motor stator windings at a controlled ramp-up rate to an amplitude to generate a controlled ramped braking torque on the motor until the motor has slowed to a defined reduced speed. Thereafter, the amplitude of the DC braking voltage is set to 0V and the motor is soft started to an amplitude and reduced frequency needed to maintain the defined reduced speed.

Abstract: An input circuit includes an interface structured to output a logic signal from an alternating current signal of a pair of elongated conductors. A load is switchable to the elongated conductors. A processor outputs a control signal to switch the load to the elongated conductors asynchronously with respect to the alternating current signal for a first predetermined time, inputs the logic signal, determines if the input logic signal is active a plurality of times during the first predetermined time and responsively sets a first state of the alternating current signal, and, otherwise, sets an opposite second state of the alternating current signal, and delays for a second predetermined time, which is longer than the first predetermined time, for the opposite second state before repeating the output, and, otherwise, delays for a third predetermined time, which is longer than the second predetermined time, for the first state before repeating the output.

Abstract: A motor-driving circuit includes: a plurality of output transistors; a first-comparator circuit to compare a voltage of each phase of driving coils of a plurality of phases in a motor, with a neutral-point voltage; a position-detecting circuit to detect a rotor position of the motor based on a comparison result of the first-comparator circuit; a switching-control circuit to supply switching signals to the plurality of output transistors according to the rotor position; and a current-limiting circuit to limit the driving currents to a first-current value so that the motor rotates at a target-rotation speed when the current-limiting circuit determines that the motor is rotating at a speed higher than or equal to a predetermined-reference-rotation speed, and limit the driving currents to a second-current value smaller than the first-current value when the current-limiting circuit determines that the motor is not rotating at the speed higher than or equal to the predetermined-reference-rotation speed.

Abstract: A motor driving circuit has a driving controlling signal generating circuit that controls a driver with a driving controlling signal, the driver supplying a driving voltage that drives the motor to the motor. The motor driving circuit has a mode selecting circuit that detects a power supply voltage supplied from a power supply to the driver, outputs a normal operation mode signal indicative of a normal operation to the driving controlling signal generating circuit if the power supply voltage is equal to or higher than a preset first threshold, and outputs a test operation mode signal indicative of a test operation to the driving controlling signal generating circuit if the power supply voltage is lower than the first threshold.

Abstract: A motor driving apparatus including a lock protection unit, a standby mode control unit, and a motor control circuit is provided. The lock protection unit receives a motor speed signal representing the rotation of the motor and generates a lock signal accordingly. The standby mode control unit receives a PWM signal and the lock signal and generates a standby mode control signal accordingly. The lock protection unit decides whether to stop generating the lock signal or not accordingly to the standby mode control signal. The motor control circuit controls the rotation of the motor according to the PWM signal and changes the operation mode according to the standby mode control signal and the lock signal.

Abstract: A differential amplifier detects a coil current Is at the time of steady rotation of a synchronous motor. An application voltage S0 at this time is detected from an output of an ATT circuit and so on. With the use of the coil current Is which is detected, the application voltage S0 at that time, and a predetermined scaling factor As, an induced current Ib is obtained based on Ib=As·S0?Is. The application voltage to the motor is controlled based on the induced current Ib which is obtained.

Abstract: Slow speed operation of a brushless DC (BLDC) motor is enhanced by gating off some of the PWM pulses in each commutation period. By doing so, longer PWM pulse widths may be used at PWM signal frequencies that are inaudible while still allowing desired slow speed operation of the BLDC motor. Centering the non-gated PWM pulses in each commutation period where peak back EMF occurs, further reduces losses and improves delivery of maximum torque from the BLDC motor.