Speed Control of PMBLDC Motor using LPC 2148 – A Practical Approach

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Int. Journal of Electrical & Electronics Engg.

Vol. 2, Spl. Issue 1 (2015)

e-ISSN: 1694-2310 | p-ISSN: 1694-2426

Speed Control of PMBLDC Motor using LPC 2148 – A Practical Approach G.A.Rathy1, P.Sivasankar2

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Assistant Professor, Electrical Department, NITTTR, Chennai, India. 2 Assistant Professor, Electronics Department, NITTTR, Chennai, India . rathysanju@gmail.com, siva_sankar123p@yahoo.com ABSTRACT: Permanent Magnet Brushless DC Motor (PMBLDC) motors are gaining popularity in industries like automotive, aircrafts, medical Appliances, electric traction, disk drive, industrial drives and instrumentation because of their high efficiency, silent operation, high power factor, reliability, compact, low maintenance and high torque to power ratio. The PMBLDC motor requires an inverter and a position sensor that exposes rotor position for appropriate alternation of current. The control in the inverter circuit is achieved using LPC 2148.The pulses generated by LPC 2148 controls the power devices of the inverter circuit. The rotation of the PMBLDC motor is built on the feedback of rotor position that is gained from the hall sensors. PMBLDC motor generally utilizes three hall sensors for deciding the commutation sequence. In this paper it is proposed to achieve a practical effective speed control of PMBLDC motor using LPC 2148. Keywords: PMBLDC Motor, Speed Control, PWM, Duty cycle, hall sensors

1. INTRODUCTION DC motors have a high starting torque. DC motors were preferred and are still often used for adjustable speed applications. The disadvantages of Brush Type DC Motors are the brushes. These brushes have to be inspected from time to time and replaced when they are worn out. So, brush DC motors have a limited life and often its life cannot easily be predicted. The windings of the DC motor are on the armature. For rapid start-stop applications the inertia of the heavy armature can be a major drawback. To overcome these drawbacks the construction of the DC motors were altered and this resulted in the Permanent Magnet Brushless DC motor. Brushless DC (BLDC) motors are rapidly gaining popularity. They offer longer life and less maintenance than conventional brushed DC motors [3]. Some other advantages over brushed DC motors and induction motors are:  Better speed versus torque characteristics  Faster dynamic response  High efficiency  Long operating life  Noiseless operation  Higher speed range. And in addition, the ratio of torque delivered to the size of the motor is higher, making them useful in applications where space and weight are critical factors [4]. 2. LITERATURE SURVEY Ravikiran et al in [1] represented the modeling of the Permanent Magnet Brushless DC (PMBLDC) motor drive NITTTR, Chandigarh

EDIT -2015

using Matlab / Simulink Software. The modelling of Permanent Magnet Brushless DC (PMBLDC) motor drive is useful in various phenomenons such as aerospace modelling and more other applications. In that Paper, the modelling of PMBLDC motor drive is done by using various components such as current, Speed controllers and sensors are installed to sense the various factors such as speed, current, and the output obtained from the inverter. The basic purpose of designing of such drive is to gives the certain ideas about designing of the motor drive using Matlab / Simulink [1] and how it helps in various applications such as electric Traction, automotive industries and more other places. Prakash et al.in [2], proposed the model for Closed Loop Controlled Buck Converter Fed PMBLDC Drive System using Simulation. Vandana Govindan et al in [5] presented digital speed control of permanent magnet brushless dc motor using TMS320F2812 DSP controller . The DSP controller used here has the special features for digital motor control. Control algorithms used for the speed control has been implemented by assembly language programming in TMS320F2812 DSP controller. According to the input command, feedback and the control algorithm, the PWM pulses for each phase is generated by the DSP and is given to the MOSFET driver. The output of the driver is 6 independent PWM pulses that have to be given to the corresponding gates of the six MOSFETs power switches used in the three-phase bridge inverter whose output is given to the stator of the Brushless DC Motor. The complete system model is simulated in MATLAB/ Simulink environment. Hardware implementation for the speed control has been achieved by programming in the DSP controller TMS320F2812 [5]. But in this paper, the speed control of PMBLDC motor is achieved using LPC 2148 microcontroller. This LPC2148 is very simple compared to TMS320F2812 DSP processor. Also writing programs to generate the PWM is much easier than DSP based system control. Also in our proposed model we experimentally control the speed of the PMBLDC motor instead of using any simulation. 3. CONSTRUCTION OF PMBLDC MOTOR In this section, the construction of PMBLDC motor will be discussed. 3.1 Stator Brushless DC motor Stator has Silicon steel stampings with slots in its interior surface. These slots accommodate a closed distributed armature windings. These windings are 128


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