Abstract: A driving system having a hollow shaft, a solid shaft arranged in the hollow shaft, a stator, a rotor connected to the hollow shaft, a clutch mechanism selectively engaged to one of the stator and the rotor, and a speed reduction mechanism having a planetary carrier assembly engaged to the clutch mechanism, and a planetary gear train connected between the solid shaft and the rotor, wherein where the clutch mechanism is engaged to the stator in a transmission manner, the planetary carrier assembly is connected with the stator, and the rotor drives the solid shaft and the hollow shaft to operate at a differential speed, and where the clutch mechanism is engaged to the rotor in the transmission manner, the planetary carrier assembly is connected with the rotor, and the rotor drives the solid shaft and the hollow shaft to operate at a same speed by the planetary gear train.

Abstract: Disclosed are a manual and remote control forward and reverse rotation control device and its control method for DC brushless ceiling fans. The control device includes a power supply, a remote control, a manual control switch assembly and a ceiling fan brushless motor which are electrically connected with one another. A gear position signal can be inputted from a remote end to determine and control the forward and reverse rotations of a brushless motor of the ceiling fan. The remote control can be connected externally by an existing control line or a manual controller module without requiring additional wiring, so as to improve the diversity of structural mechanism, increase the versatility of remote operation, and achieve good functionality and variability of applications.

Abstract: A method of position estimation including: a signal detection step in which N (where N is an integer of 3 or more) sensors each detect a magnetic field which is in accordance with a position of a mover and output a detection signal as an electrical signal, the detection signals being displaced in phase by an angle obtained by dividing 360 degrees by N; a crossing detection step in which a crossing detection section sequentially detects a crossing at which each detection signal having been output through the signal detection step crosses another; a subdivision detection step in which a subdivision detection section detects a portion of the detection signal that connects from a crossing to another crossing which is adjacent to that crossing, as one or more subdivision signals; and a line segment joining step in which a line segment joining section sequentially joins the subdivision signals and estimates the position of the mover based on the plural subdivision signals having been joined, to generate an estimate

Abstract: This motor device includes: a motor having components including a stator and a rotor; and a controlling circuitry to control the motor. The motor is provided with temperature sensors to detect a heat transfer amount and a transfer direction about the components. The controlling circuitry includes a temperature calculator to calculate a component temperature based on a thermal circuit network from thermal resistances and heat capacities given for the components. On the basis of actual measured values of the heat transfer amount and the transfer direction obtained by the temperature sensors, the temperature calculator corrects thermal resistances and heat capacities about the components obtained on the basis of the thermal circuit network, and estimates the temperature of each component during driving of the motor.

Abstract: A vehicle is provided. The vehicle includes an electronic control unit and a pedal assembly. The electronic control unit selectively switches between a powered off state and a powered on state. The pedal assembly includes pedal arm, a target, and a switch. The pedal arm moves between a plurality of positions. The target moves with the movement of the pedal arm. The target generates a magnetic field strength. The switch activates when the magnetic field strength of the target exceeds a predetermined threshold. When the switch activates, a signal is sent to the electronic control unit to activate the electronic control unit from the powered off state to the powered on state.

Abstract: Electronic equipment includes a center frame, a first motor, a second motor, and a drive module. The first motor and the second motor are fixed respectively at a first designated location and a second designated location of the center frame. The drive module is electrically connected respectively to the first motor and the second motor. The drive module is adapted to drive, according to a control signal, the first motor or the second motor to vibrate independently, or drive the first motor and the second motor to vibrate synchronously.

Abstract: A method for use in a sensor includes generating a first signal by a first sensing module in response to a magnetic field associated with a rotating target, generating a base word based on the first signal, the base word including a first base bit that is generated by comparing respective components of the first signal, reversing a respective polarity of the first signal and offsetting the first signal, generating a test word based on the first signal, the test word being generated after the respective polarity of the first signal is reversed and the first signal is offset, the test word including a first test bit that is generated by comparing the respective components of the first signal, and setting a value of an error signal based on whether the test word matches the base word.

Abstract: An electric motor includes a stator, a rotor, and a magnetic sensor. The stator has an iron core and a magnetic flux coil. The rotor has a rotary shaft and a cylindrical rotor magnet. The magnetic sensor has a sensor unit that outputs an electric signal based on an applied magnetic flux. The rotor magnet is disposed so as to face the iron core of the stator. The rotor magnet has a main magnet unit and a sensor magnet unit that is formed integrally with the main magnet unit and has an external diameter smaller than an external diameter of the main magnet unit. The magnetic sensor is disposed beside the sensor magnet unit. An outer circumferential edge of the sensor magnet unit is located farther away from the rotary shaft than a center of the sensor unit. The magnetic sensor is configured such that a center of the sensor unit and a center of the magnetic sensor do not match each other, and the center of the sensor unit is closer to the sensor magnet unit than the center of the magnetic sensor.

Abstract: A power conversion system includes an inverter and a controller configured to: responsive to startup of the system, measure a motor speed of the IPM motor; responsive to the motor speed being less than a threshold, generate the inverter switching control signals to perform high frequency injection (HFI); during the HFI, determine a measured angle of the IPM motor; during the HFI, generate the inverter switching control signals to provide an injected current to the IPM motor; detect acceleration or deceleration of the IPM motor responsive to the injected current; selectively determine an electrical angle as half the measured angle or as 180 degrees plus half the measured angle based on the detected acceleration or deceleration of the IPM motor; and responsive to determining the electrical angle, generate the inverter switching control signals to drive the IPM motor to a reference frequency in a normal operating mode of the inverter.

Abstract: A switch control system for a motor and a lamp of a fan includes a motor switch, a lamp switch, a detection unit, a wireless remote control receiving unit, a control unit, and a drive unit. The control unit is electrically connected to the motor switch through a motor power processing part. The control unit is electrically connected to the lamp switch through a lamp power processing part. Thus, the motor switch and the wireless remote control receiving unit are able to operate and control the motor independently, and the lamp switch and the wireless remote control receiving unit are able to operate and control the lamp independently.

Abstract: An offset of an output voltage of a magnetic sensor caused by an external magnetic field is removed. A motor according to a disclosed embodiment includes: a first magnetic sensor that detects a rotational position of a rotor; a second magnetic sensor that is arranged at a predetermined mechanical angle with respect to the first magnetic sensor and detects the rotational position of the rotor; a signal amplifier that amplifies a difference between a first signal which is a signal output from the first magnetic sensor and a second signal which is a signal output from the second magnetic sensor; and a pulse signal generator that converts an output signal of the signal amplifier into a pulse signal.

Abstract: An offset of an output voltage of a magnetic sensor caused by an external magnetic field is removed. A motor according to a disclosed embodiment includes: a first magnetic sensor that detects a rotational position of a rotor; a second magnetic sensor arranged at a position shifted by ?/N in a rotation direction of the rotor with respect to the first magnetic sensor when the number of pole pairs is N; a signal amplifier that amplifies a difference between a first signal which is a signal output from the first magnetic sensor and a second signal which is a signal output from the second magnetic sensor; and a pulse signal generation unit that converts an output signal of the signal amplifier into a pulse signal.

Abstract: An unmanned aerial vehicle (UAV) includes a UAV body, and a stabilizing platform mounted on the UAV body and configured to stabilize a payload device. The stabilizing platform includes a frame assembly adapted to hold the payload device and a brushless motor coupled to the frame assembly. The brushless motor is configured to directly drive the frame assembly in response to one or more motor signals to allow the payload device to rotate around at least one of a pitch axis, a roll axis, or a yaw axis of the payload device. A brushless motor includes a rotor housing; a stator disposed within the rotor housing; and a linear Hall effect sensor. A posture of the payload device is controlled by adjusting a rotational angle of the brushless motor, and the rotational angle of the brushless motor is determined using the linear Hall effect sensor.

Abstract: Described is a sensor-less motor reversal (“SLMR”) apparatus that aids the reversal of motor rotation of a bidirectional motor, such as a brushless DC motor of an aerial vehicle. The SLMR includes an RPM dependent clutch that is rotated by a drive shaft of the motor and that engages an engageable shaft of the SLMR apparatus during a low RPM range of the motor during which indirect measurement of the RPM of the motor through a back-EMF of the motor is unreliable. As the engageable shaft increases in RPM, energy is stored by an energy storage mechanism of the SLMR. As the RPM of the motor decreases as part of a motor reversal, the energy stored by the energy storage mechanism is discharged and aids in the transition of the reversal of the motor from positive to negative, or negative to positive. As described, the SLMR apparatus is stateless.

Abstract: An apparatus and a method for redundant measurements of a magnetic field originating from or influenced by a moveable object is described. The apparatus comprising at least one first magnetic field sensitive element measuring at least one magnetic field property of the magnetic field, wherein the at least one first magnetic field sensitive element is implemented on a first area of a semiconductor substrate, at least one second magnetic field sensitive element measuring at least one magnetic field property of the magnetic field, wherein the at least one second magnetic field sensitive element is implemented on a second area of said semiconductor substrate, and wherein the first and second areas are isolated from one another.

Abstract: A method of performing scalar-based control of a motor connected to a power converter via at least one passive electrical reactance component, wherein the method includes: estimating a motor current at terminals of the motor to thereby obtain an estimated motor current, and controlling the power converter based on the estimated motor current.

Abstract: The present disclosure relates to a compressor control apparatus and a compressor control method thereof, and more particularly, to a compressor control apparatus for controlling a switching operation of a switching device to control the start-up of a compressor motor and a compressor control method thereof.

Abstract: In a DC brushless ceiling fan speed control device and method, the control device includes a switch module having a switch body, a power supply connected to a side of the switch body, and first, second, and third wire connecting members connected to the other side of the switch body. The second and third wire connecting members have a forward diode and a reverse diode respectively, and the switch body is provided for controlling the input of a power supply to directly and electrically supply power to the first wire connecting member, or supply power to the second and third wire connecting members through the forward and reverse diodes. When current is inputted, the waveform signal will be different, and this phenomenon is used for controlling the rotating speed of a ceiling fan to achieve the effects of good safety and convenience.

Abstract: An electronic device and a magnetic sensor integrated circuit thereof are provided. The magnetic sensor integrated circuit includes a shell, a semiconductor substrate installed in the shell and a first to a third port extending from the shell. A rectifier and a position sensor are provided on the semiconductor substrate. The rectifier includes first and second output terminals and two input terminals respectively connected to the first and second ports. In a case that the first and second ports are positively or negatively connected to an external power supply, a voltage output by the first output terminal of the rectifier is higher than the voltage output by the second output terminal of the rectifier. The position sensor is connected to the first and second output terminals of the rectifier, and a magnetic field signal detected by the position sensor is output by the third port.

Abstract: A driving device for a brushless DC motor having at least one coil may include a voltage zero crossing detection unit to where an induced voltage becomes zero; a detection period setting unit to set at least one detection period synchronously with the voltage zero crossing point; a coil voltage detection comparator to compare a terminal voltage generated from one end of the coil with a threshold voltage, and generate a coil voltage detection signal indicating a comparison result; a current phase detection unit to generate a phase detection signal indicating a relationship between a phase of a coil current flowing through the coil and a phase of the induced voltage; a driving signal synthesis unit to generate a driving control signal based on the phase detection signal; and a driving circuit to drive the brushless DC motor based on the driving control signal.

Abstract: A variable-flux motor drive system including a permanent-magnet motor including a permanent magnet, an inverter to drive the permanent-magnet motor, and a magnetize device to pass a magnetizing current for controlling flux of the permanent magnet. The permanent magnet is a variable magnet whose flux density is variable depending on a magnetizing current from the inverter. The magnetize device passes a magnetizing current that is over a magnetization saturation zone of magnetic material of the variable magnet. This system improves a flux repeatability of the variable magnet and a torque accuracy.

Abstract: A non-contact adjustable hysteretic magnetic encoder includes a bipolar magnetic block, two magnetic sensing components, a storage, and a controller. After retrieving the current rotation angle by accessing a rotation angle table, the controller determines, by an encoding rule, digital logical values of a first phase signal (A-phase signal) and digital logical values of a second phase signal (B-phase signal) and outputs the digital logical values. The phase difference between a first phase signal and a second phase signal is adjusted, and a hysteresis range, also known as hysteresis angle, is adjusted, according to the grids attributed to the predetermined number of grids before the turning point and the grids attributed to the predetermined number of grids after the turning point. Hence, the non-contact adjustable hysteretic magnetic encoder features enhanced potential of expansion and marked industrial practicability.

Abstract: A control system for an electric motor, the control system comprising a first control device arranged to control current in a first coil set of the electric motor and a second control device arranged to control current in a second coil set of the electric motor; wherein the first control device includes a first interface arrangement for receiving data from a first controller for allowing the first control device to determine a required current flow in the first coil set, wherein the first interface arrangement is arranged to communicate data to the second control device for allowing the second control device to determine a required current flow in the second coil set.

Abstract: A switching controller of a poly-phase electric motor may generate, in a fully digital manner, a replica of the phase current and/or of the phase (star) voltage of one or more windings of the motor. The switching controller may use digital signals already available for driving the motor to reconstruct a replica of the phase current or the phase voltage, and thereby avoid the need for dedicated analog components for phase current or phase voltage determination.

Abstract: There is provided a method for determining an abnormality during operation of a high voltage disconnect switch, the method comprising: determining a current position of an arm of the high voltage disconnect switch operatively connected to a motor, the motor being operated for driving the arm of the high voltage disconnect switch; determining a torque of the motor corresponding to the current position of the arm; comparing the torque of the motor to a torque threshold for the current position of the arm; and outputting an abnormality signal based on the comparison.

Abstract: An electrical controller for electric motors is provided. A control system for an electric motor comprises a supply for supplying excitation current to different windings of the motor at any given time. Furthermore, the amplitude of the excitation current is independently variable of the timing and duration of the application of the excitation current to the windings. This allows increased control of the motor and facilitates the operation of the motor at high mechanical and/or electrical speeds.

Abstract: There is provided a motor controlling circuit including: a hall signal level detecting unit detecting a hall signal from a hall sensor; and a signal generating unit sensing a change in a level of the hall signal to generate a motor controlling signal according to the change in the level of the hall signal, wherein the signal generating unit determines that the hall signal is maintained at a high level in a case in which a high level maintaining time of the hall signal is equal to or shorter than a preset time.

Abstract: The three-phase motor driving apparatus according to an aspect of the present invention comprises a controlling part that estimates a rotational position of the three-phase brushless motor based on a reference pulse signal output by the rotor sensor according to a rotational position of the magnetic pole of the first phase of the rotor when the three-phase brushless motor rotates, and controls the motor driver in driving patterns sequentially prescribed so as to correspond to the estimated rotational position of the three-phase brushless motor.

Abstract: The present invention provides a gas delivery device and system and methods for delivering humidified pressurized gas through a conduit to a subject. The configuration of the elements of the gas delivery device enable the device to be conveniently oriented from a horizontal to vertical position to suit the needs of a user. The gas delivery device may incorporate a Helmholtz resonator for dampening sound of the motor. The conduit may incorporate concentric tubes to allow it to conveniently engage the humidifier at a single aperture. The invention includes a method of operating a blower motor for a gas delivery device using a single Hall sensor.

Abstract: A washing machine and a control method thereof capable of determining whether a driving motor is locked. A pulsator is rotatably mounted in a spin basket, a driving motor generates rotational force, a clutch transmits the rotational force to the pulsator or the spin basket, a driving circuit supplies a driving current to the driving motor, and a control unit controls the driving circuit and the clutch so that the pulsator rotates in a forward or reverse direction and rotation of the spin basket is stopped in a washing or rinsing process. The control unit controls the driving circuit so that a motor lock detection current is supplied to the driving motor, and controls the clutch so that, if a rotating speed of the driving motor is less than a reference speed, the rotational force is transmitted only to the pulsator.

Abstract: The outputs from a first magnetic detector and a second magnetic detector are supplied to first to fourth output circuits which are differential amplifiers, whereby first and second detected outputs which are analogous to a sine wave and whose positive-negative polarities are opposite to each other, and third and fourth detected outputs which are analogous to a cosine wave and whose positive-negative polarities are opposite to each other are obtained. The first to fourth detected outputs are supplied to a switching circuit, and detected output portions are obtained at intervals of 90° from the first to fourth detected outputs. A bias adding circuit applies a bias voltage to each of the detected output portions to obtain an angle detection output analogous to a linear function. The angle detection output is used to determine the supply timing at which a three-phase driving current is supplied.

Abstract: Disclosed herein are a biasing circuit for a hall sensor and a hall amplifier in a motor driving circuit, the biasing circuit including: a regulator installed inside a singled packaged chip, supplied with external power, and regulating the external power in voltage appropriate for a circuit to supply the regulated voltage; the hall amplifier supplied with the voltage regulated from the regulator, receiving an output signal from the hall sensor outside the chip, and amplifying the output signal to output the amplified signal; first and second resistors supplied with the voltage from the regulator to generate an input voltage common mode (VCM) of the hall amplifier; and third and fourth resistors supplied with the voltage from the regulator to generate an input VCM of the hall sensor.

Abstract: An integrated servo system and a method of controlling a motor is provided. The integrated servo system includes a position detector which determines original position data of a motor and a position signal processor which determines a position of the motor based on the determined position data. The integrated servo system further includes a servo controller circuit which controls the motor based on the determined position data and a parallel bus through which the determined position data is transmitted from the position signal processor to the servo controller circuit.

Abstract: A motor assembly that includes a motor (102) having a rotatable shaft, a hub coupled to the rotatable shaft, the hub having a propeller indexer to receive a propeller (104), when the propeller is present, a sensor trigger rotatable with the shaft (100) and positioned at a propeller offset angle ?PROP from the propeller indexer, and a sensor coupled to the motor and positioned to detect the sensor trigger so that the propeller indexer may be positioned at the propeller offset angle ?PROP from the sensor through rotation of the shaft so that said sensor is proximate to the sensor trigger.

Abstract: A motor includes a rotor, a sensor unit, an offset unit, a rectification unit and a modulating unit. The sensor unit outputs a first signal in accordance with a magnetic field variation of the rotor. The offset unit is coupled to the sensor unit, and outputs a second signal in accordance with the first signal. The rectification unit is coupled to the offset unit, and outputs a third signal in accordance with the second signal. The modulating unit is coupled to the rectification unit, and outputs a control signal in accordance with a result by comparing the third signal with a periodic signal. The modulating unit controls a reverse rotation of the rotor smoothly in accordance with the control signal. A control method of the motor is also disclosed.

Abstract: The present invention discloses a mechanical equipment. The sensing member and the sensed member are mounted on the power device, and one of the sensing member and the sensed member is mounted on the output mechanism to move periodically as the output mechanism moving periodically. When each time the sensing member and the sensed member are located relatively at a predetermined position, the control device receives the sensing signal generated when the sensing member senses the sensed member and sends a predetermined control command to the power mechanism when the sensing signals received by the control device reach the threshold value. Therefore, the present invention can achieve controlling the working state of the mechanical equipment and reduce the failure probability of the mechanical equipment at the same time.

Abstract: A fan motor driving device driven based on a pair of out-of-phase Hall signals may include a first driving portion, configured to (i) amplify a difference of the pair of the Hall signals with a first polarity and generate a first control signal, and (ii) switch between a driving status and a regeneration status; a second driving portion, configured to (i) amplify the difference of the pair of the Hall signals with a second polarity, and generate a second control signal, and (ii) switch between a driving status and a regeneration status; and a regeneration controller, controlling statuses of the first driving portion and the second driving portion, respectively.

Abstract: A brushless direct current three-phase motor that is self driven and therefore does not require externally generated waveforms for its operation. The circuit connected to the motor is analog and reduces the complexity and present cost of the driver circuitry. There is no electronic commutation of the currents in the stator coils as is the case with other brushless motors.

Abstract: Some embodiments provide a system that generates a coil switching signal for a brushless DC motor. During operation, the system determines a magnetic field of the brushless DC motor at a first time and a magnetic field of the brushless DC motor at a second time. Then, the coil switching signal is generated based on a relationship between the magnetic field determined at the first time and a first predetermined threshold, and the magnetic field determined at the second time and a second predetermined threshold.

Abstract: A drive unit, which can be included in an image forming apparatus with peripherals disposed thereto and use a control method therefore, includes an inner rotor brushless DC motor, a driver, a rotation detector, and a controller. The driver supplies power to drive the brushless DC motor. The rotation detector detects an amount and direction of rotations of an output shaft. The controller controls the rotations of the brushless DC motor and obtains a target drive signal of the brushless DC motor externally and a detection signal from the rotation detector and outputs a signal to the driver. The controller controls a speed of rotation of the brushless DC motor by varying the signal output to the driver based on the target drive signal and the detection signal.

Abstract: An integrated circuit for controlling an electric motor, which has a primary component with a coil and a permanently magnetic secondary component cooperatively connected via an air gap to the primary component, has a semiconductor substrate in which are integrated a microcontroller and/or a pre-amplifier for controlling the coil of the electric motor. For detecting the position of the permanently magnetic secondary component, at least two magnetic field sensors with their measurement axes aligned crosswise relative to each other are integrated in the semiconductor substrate.

Abstract: An electric motor or generator system comprising a rotor having a first set of magnet poles; a stator having a first sensor mounted on the stator and a second sensor mounted in substantially a diametrically opposite position on the stator relative to the first sensor, wherein the first sensor is arranged to output a first signal indicative of a first rotor flux angle associated with the first set of magnet poles as the rotor rotates relative to the stator and the second sensor is arranged to output a second signal indicative of a second rotor flux angle associated with the first set of magnet poles as the rotor rotates relative to the stator; and means arranged to determine a corrected rotor flux angle by averaging the first rotor flux angle indicated by the first sensor and the second rotor flux angle indicated by the second sensor.

Abstract: A household appliance including a fan speed controller, and a method of controlling fan speed of a household appliance, are provided. The system includes a fan speed controller that cut a voltage to the fan motor, measures an electromotive force (EMF) of the fan motor at a predetermined time after the cutting of the voltage to the fan motor, and compares the measured electromotive force (EMF) to a table.

Abstract: In a method for the determination of a current initial rotational position of a rotor and in an arrangement for carrying out same, an incremental position encoder outputs an output signal. The output signal is produced by superposition of a chronologically random and systematically fluctuating signal interference on a basic signal, and composed of at least two component signals which change periodically in accordance with the rotational position of the rotor and are in a fixed angular relationship to one another. To determine the position, the output signal is used exclusively. The current initial rotational position of the rotor relative to a reference initial rotational position is determined by comparing the time profile of the portion of the systematically fluctuating signal interference of a current measured value sequence of the signal and the measured values of a signal sequence acquired starting from the reference initial rotational position.

Abstract: A detection control system includes a sensing unit, a control module and a driving module for a motor including a rotor and a stator. The sensing unit electrically connects the motor to sense a first and a second magnetic pole of the rotor cross a chip disposed between the rotor and the stator; a third magnetic pole is alternated to a forth magnetic pole of the stator to generate a sensing signal. A detection unit of the control module detects a kickback voltage value generated by a first current value changing to a second current value to calculate a minimum current value to generate a detecting signal. A timing unit receives the sensing and the detecting signal to calculate a first and a second period of time, and a discharging time. The driving module drives the rotor by receiving a control signal the control unit generates by controlling an alternating time.

Abstract: A rotating electromechanical machine has a rotor having at least one current-carrying winding and at least one rotor-mounted sensor configured to sense a machine property or parameter during machine operation. Rotor-mounted circuitry dynamically modifies at least one property of the current-carrying winding during machine operation in response to the sensed machine property or parameter.

Abstract: A fault detection system for an over-speed protection system of a rotating machine includes a first speed sensor, second speed sensor, and third speed sensor sensing a speed of a shaft of the rotating machine. The system includes a first input configured to receive a first pulse train from the first speed sensor, a second input configured to receive a second pulse train from the second speed sensor, a third input configured to receive a third pulse train from the third speed sensor, and a processor configured to generate a shutdown signal for the rotating machine based on the first pulse train, the second pulse train, and the third pulse train.

Abstract: A DC brushless motor includes a rotary actuation shaft having multiple poles. Each of the poles has multiple commutation steps. The DC brushless motor also includes a motor controller capable of controlling rotation of the rotary actuation shaft. The motor controller stores a commutation step map.

Abstract: A drive unit, which can be included in an image forming apparatus with peripherals disposed thereto and use a control method therefore, includes an inner rotor brushless DC motor, a driver, a rotation detector, and a controller. The driver supplies power to drive the brushless DC motor. The rotation detector detects an amount and direction of rotations of an output shaft. The controller controls the rotations of the brushless DC motor and obtains a target drive signal of the brushless DC motor externally and a detection signal from the rotation detector and outputs a signal to the driver. The controller controls a speed of rotation of the brushless DC motor by varying the signal output to the driver based on the target drive signal and the detection signal.

Abstract: A motor assembly (101), comprising a brushless DC motor (102) with control electronics (103) which comprises at least two magnetic field sensors adapted to measure magnetic flux from magnetic poles on a rotor in the brushless DC motor (102). The magnetic field sensors are adapted to determine an angular position of the rotor, with the purpose of controlling the current to the brushless DC motor based on the determined angular position. The brushless DC motor is an external rotor motor (102) comprising an internal stator (104), and an external rotor (105) having a periphery (106) and an inside (107), which exhibits a plurality of permanent magnets (108, 109, 110, 111) disposed at regular intervals along the inside (107) to provide the magnetic poles.