scispace - formally typeset
Search or ask a question
Author

Andras Lelkes

Bio: Andras Lelkes is an academic researcher from ebm-papst. The author has contributed to research in topics: AC motor & Voltage. The author has an hindex of 10, co-authored 45 publications receiving 295 citations.

Papers
More filters
Patent
21 Sep 1999
TL;DR: In this article, a controllable electronic switching device is connected upstream of the motor and is actuated by a control unit such that a sinusoidal input AC voltage is used to produce a motor AC voltage which can be varied in order to change the rotation speed.
Abstract: The present invention relates to a system for controlling the rotation speed of AC motors, in particular single phase motors. In this case, a controllable electronic switching device is connected upstream of the motor and is actuated by a control unit such that a sinusoidal input AC voltage is used to produce a motor AC voltage which can be varied in order to change the rotation speed. The control unit is designed in such a manner that the fundamental frequency and/or the amplitude of the motor AC voltage can be varied by phase gating.

35 citations

Proceedings ArticleDOI
20 Jun 2004
TL;DR: In this article, the authors describe methods for the automatic optimization of motor efficiency by changing the commutation angle, which can reduce motor current and power consumption in brushless DC motors.
Abstract: Brushless DC motors are often used in fan applications due to their easy speed controllability, high efficiency and long life time expectation. These motors are electronically commutated; the commutation point is determined by Hall-sensors or sensorless (mainly by the so called back EMF method). In case of constant commutation angle, this angle can be optimized only for one operating point. Through this optimization, motor current and power consumption can be reduced. However, if the motor works in another operating point (different supply voltage, speed and/or torque), its efficiency will be lower than that of a motor with a commutation angle optimized for this new operating point. This paper describes methods for the automatic optimization of motor efficiency by changing the commutation angle.

35 citations

Proceedings ArticleDOI
10 Dec 2002
TL;DR: An important market for brushless DC (BLDC) motors is fan applications, where low acoustic noise is of increasing importance, and noise has been reduced significantly using new modulation strategies.
Abstract: An important market for brushless DC (BLDC) motors is fan applications, where low acoustic noise is of increasing importance. External rotor motors are especially advantageous for space-saving fan-motor-units. The acoustic noise of the motor can be influenced considerably through commutation strategy. The commutating process has been analyzed using space vectors. Motor noise has been reduced significantly using new modulation strategies.

30 citations

Patent
23 Sep 2004
TL;DR: In this article, a method for the commutation of a brushless direct current motor having at least one motor winding in which the position of the rotor with respect to the stator is determined and a commutation signal is generated from this, and the motor winding is energized by a preset commutation angle as a function of the signal.
Abstract: The invention relates to a method for the commutation of a brushless direct current motor having at least one motor winding in which the position of the rotor with respect to. the stator. is determined and a commutation signal is generated from this, and the motor winding is energized by a preset commutation angle as a function of the commutation signal: Depending on the construction and energization of the motor, the invention provides that the polarity of the winding, current is registered when a commutation signal appears, and the commutation 10angle is changed as a function of the recorded polarity of the winding current in such a way that the winding current is essentially zero or has a zero point when a commutation signal, appears, or, that when a commutation signal appears, the absolute value of the winding currents is measured and the commutation angle is changed as a function of the polarity of the winding current in such a way that the total excitation of the momentary phase calculated from the winding currents is essentially zero when a commutation signal appears.

25 citations

Patent
23 Nov 2004
TL;DR: In this article, a method to optimize the efficiency of a motor operated under a load having an essentially quadratic characteristic curve was proposed, the motor being connected to a motor control with whose aid at least one free motor parameter w can be changed to influence the efficiency.
Abstract: The invention relates to a method to optimize the efficiency of a motor operated under a load having an essentially quadratic characteristic curve, the motor being connected to a motor control with whose aid at least one free motor parameter w can be changed to influence the efficiency. According to the invention, the rotational speed n and the input power P E are determined and the motor parameter w is adjusted to a value at which the value E representing the quotient of the cube of the rotational speed n and the input power P E attains a maximum.

21 citations


Cited by
More filters
Journal Article
TL;DR: In this article, the authors present state-of-the-art PMBLDC motor drives with an emphasis on sensorless control of these motors, where the rotor position is estimated from the voltage and current signals, which are easily sensed.
Abstract: Permanent magnet brushless DC (PMBLDC) motors are the latest choice of researchers due to their high efficiency, silent operation, compact size, high reliability and low maintenance requirements. These motors are preferred for numerous applications; however, most of them require sensorless control of these motors. The operation of PMBLDC motors requires rotor-position sensing for controlling the winding currents. The sensorless control would need estimation of rotor position from the voltage and current signals, which are easily sensed. This paper presents state of the art PMBLDC motor drives with an emphasis on sensorless control of these motors.

117 citations

Patent
James E. Masino1
12 Jun 2003
TL;DR: In this paper, a digital adaptive controller circuit is presented for commutating a brushless, sensorless, DC motor in either of two directions adapted to receive digital back electromotive force (BEMF) detector (130) signals.
Abstract: A digitally adaptive controller circuit (100) for commutating a brushless, sensorless, DC motor (110) in either of two directions adapted to receive digital back electromotive force (BEMF) detector (130) signals. The digital circuit is driven by an input clock that is adjustable to configure the motor controller for use with a broad range of DC motors. The circuit includes commutational logic that decodes a current commutational state and a user-definable binary direction input into logic levels for digital control signals for controlling motor drive switches. The circuit also includes a signature analyzer to compare logic levels in the BEMF detector (130) signals with expected logic levels based on an expected rotor position and direction of rotation. The digital circuit commutates the motor (110) if the logic levels in the BEMF detector (130) signals are at the expected logic levels. The digital circuit is compact and simple enough to be deployed onto a single programmable logic device.

105 citations

Patent
21 Oct 1999
TL;DR: In this paper, an analogous circuit with two current limiting members (131, 161) is provided and a circuit in which these functions are realized by the software of a microcontroller so that the measurement of current is no longer necessary.
Abstract: The invention relates to an electronically commutated motor in which both the drive current (i2) and the brake current (i2') are monitored. If the drive current is too high, a pulse duty factor is reduced that influences the current in the motor. If the brake current is too high, said pulse duty factor is increased. To this end, an analogous circuit with two current limiting members (131, 161) is provided and a circuit in which these functions are realized by the software of a microcontroller so that the measurement of current is no longer necessary. A combination of the two methods is also possible according to which hardware current limitation and software current limitation interact.

88 citations

Patent
29 Mar 2011
TL;DR: In this paper, a brushless motor is controlled by exciting a winding of the motor for a conduction period over each electrical half-cycle of a motor, defined by a waveform that varies periodically with time.
Abstract: A method of controlling a brushless motor, the method comprising 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.

87 citations

Patent
20 Jan 2011
TL;DR: In this article, a centrifugal blood pump was presented, where one permanent magnet was provided in one surface of an impeller, a second permanent magnet is provided in an inner wall of a blood chamber, a third permanent magnet and a rotor for driving the impeller to rotate are provided, with an diaphragm being interposed.
Abstract: In this centrifugal blood pump apparatus, one permanent magnet is provided in one surface of an impeller, a second permanent magnet is provided in an inner wall of a blood chamber, a third permanent magnet is provided in the other surface of the impeller, and a fourth permanent magnet and a rotor for driving the impeller to rotate are provided, with an diaphragm being interposed. An amount of change in attractive force between the first permanent magnet and the second permanent magnet and an amount of change in attractive force between the third and fourth permanent magnets when the impeller is eccentric are made substantially equal to each other. Therefore, a levitation position of the impeller can always be maintained at a substantially central position in a housing.

84 citations