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.

https://www.koreascience.or.kr:443/article/JAKO200906942466561.pdf

State of the Art on Permanent Magnet Brushless DC Motor Drives

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.

Electronically commutated motor

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.

Control of a brushless motor

Permanent magnet synchronous machines (PMSMs) with fractional-slot non-overlapping windings, also known as tooth-coil winding PMSMs (TCW PMSM), have been under intensive research during the latest decade. There are many optimization routines explained and implemented in the literature to improve the characteristics of this machine type. This paper introduces a new technique for torque ripple minimization in TCW PMSM. The source of torque harmonics is also described. The low-order torque harmonics can be harmful for a variety of applications, such as direct drive wind generators, direct drive light vehicle electrical motors, and for some high-precision servo applications. The reduction of the torque ripple harmonics with the lowest orders (6th and 12th) is realized by machine geometry optimization technique using finite element analysis. The presented optimization technique includes the stator geometry adjustment in TCW PMSMs with rotor surface permanent magnets and with rotor embedded permanent magnets. Influence of the permanent magnet skewing on the torque ripple reduction and cogging torque elimination was also investigated. It was implemented separately and together with the stator optimization technique. As a result, the reduction of some torque ripple harmonics was attained.

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Unequal Teeth Widths for Torque Ripple Reduction in Permanent Magnet Synchronous Machines With Fractional-Slot Non-Overlapping Windings

A method and apparatus for controlling a brushless DC (BLDC) motor over a wide range of angular speeds is presented Analog magnetic sensors provide continuous signal measurements related to the rotor angular position at a sample rate independent of rotor angular speed In one embodiment, analog signal measurements are subsequently processed using an arctangent function to obtain the rotor angular position The arctangent may be computed using arithmetic computation, a small angle approximation, a polynomial evaluation approach, a table lookup approach, or a combination of various methods In one embodiment, the BLDC rotor is used to drive a Roots blower used as a compressor in a portable mechanical ventilator system

Compressor control system for a portable ventilator

The invention relates to a system for the electronic commutation of a brushless DC motor (1) having three phase windings (u, v, w) which are electrically displaced by 120°, comprising a semiconductor bridge (4) consisting of six power semiconductors (S1 to S6), which drives the phase windings (u, v, w) for generating a rotating magnetic stator field, a control unit (6) which correspondingly drives the power semiconductors (S1 to S6), and a device for detecting the respective rotational position of a rotor exhibiting a permanent-magnetic magnet wheel, the device for detecting the rotor position being constructed as sensor-less evaluating unit (8), for evaluating the voltage induced by the rotating magnet wheel which can be measured at the winding terminal (U, V, W) of the motor which is not currently driven. It is the object of the present invention to achieve a reduction of running and commutation noises whilst maintaining the inexpensive and fault-insensitive sensorless rotor position detection. For this purpose, the control unit (6) drives the power semiconductors (S1 to S6) in twelve switching states, which are different with respect to the magnetic field direction effected in each case, by means of a 12-step commutation over one electrical revolution of the DC motor in dependence on the rotor positions.

System for the electronic commutation of a brushless DC motor

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.

System for controlling the rotation of AC motors

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.

Low-noise external rotor BLDC motor for fan applications

Method for electronic switching of a brushless direct current motor (1) with a permanent magnet rotor (4) and a stator (2) with a number of angularly displaced windings (a, b, c). The winding currents (i a, i b, i c) are defined by the curves of the induced pole wheel voltages so that cause a predefined motor torque via the rotor rotation. The torque is applied via the rotor in a continuous jump-free manner. INDEPENDENT CLAIM included for 1) control system for electronic switching of a brushless direct current motor, 2) brushless direct current electric motor.

Method and control system for electronic commutation of brushless DC motors

of EP1073192The ac motor has a Sine wave input (Un) that is rectified an sent to the drive stage (2). At the same time the zero cross over point is detected and fed into the controller (6) together with the speed setting (14) zero cross over detection (10) signal of the current to the motor load (L).

Jens Krotsch

Papers

System for the electronic commutation of a brushless DC motor

System for controlling the rotation of AC motors

Low-noise external rotor BLDC motor for fan applications

Method and control system for electronic commutation of brushless DC motors

Method and device for driving an AC load, especially an AC motor with speed control