Saturday, September 17, 2011

Brushless DC Motor Control Using PLC





Brush DC motors have been utilized in industry because of their linear typical and the easiness of correcting their speed throughout a easy of power circuit electronic. The commutator utilized in brushed DC motors is the major disadvantage from such systems which has inspired the researchers to straight their studies on the road to AC systems, synchronous and induction motors. As the last decade, the motors of induction have led the industry because of the accessibility of the variable speed drives of induction motors. Nevertheless, these motors run at medium efficiency particularly those of little power ratings. The drawbacks brushed solution motors of AC and DC can be established onto BLDCMs, with better performance. BLDCM have alike features to the independently stimulated DC machines but their control is similar to the machines control of AC. This article investigates the likelihood of using a PLC to manage thus motors than microcontrollers.

Brushless DC motors can be separated into categories, BEMF Sinusoidal and BEMF Trapezoidal. The current learn arrangements with a motor BLDC with a BEMF trapezoidal. BEMF of BLDCM has a wave form of trapezoidal and the winding stator is supplied by a current of rectangular to generate constant torque. The three stage windings are put on the rotor and the stator (with magnets) is free to shift. There are always two stages on at any one time to offer continuous torque.

The whole scheme for a BLDCM which demonstrates the cycle followed to take such systems. As it is known, the controller passes the time the signals provided by the sensors position. Then, the controller gets an achievement biasing the power transistors to change them on or off so that the motor windings are powered based on the position of rotor. The motor will operate constantly as the system makes an action loop.

The PLC of Toshiba T1-16s was utilized. The PLC contains phototransistors, 2 transistors and 6 relay outputs, 8 inputs, and 8 outputs which are mostly used to supply PWM or clock signal. The majority of the results are outputs of relay that are not quick enough to give quick exchanging and consist little life span. To conquer this, a card of transistor output, type sink, is added to the PLC, so that all the signals of output are acquired from these transistors. The circuit of driving is realized to make six controlling of power MOSFETs the BLDCM.



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