MODELING AND SIMULATION OF BLDC MOTOR BY USING MATLAB

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Available Online at www.ijpret.com 122

INTERNATIONAL JOURNAL OF PURE AND

APPLIED RESEARCH IN ENGINEERING AND

TECHNOLOGY

A PATH FOR HORIZING YOUR INNOVATIVE WORK

MODELING AND SIMULATION OF BLDC MOTOR BY USING MATLAB

MS. RUTUJA A. BHAT1, PROF. P. S. JADHAV2, MS. KSHITIJA A. BHAT3

1. Department of Electrical Engineering, PES Modern College of Engineering, Pune, Maharashtra, India.

2. Assistant Professor, Department of Electrical Engineering, PES Modern College of Engineering, Pune, Maharashtra, India. 3. Department of Mechanical Engineering, OM College of Engineering, Inzapur, Wardha, Maharashtra, India.

Accepted Date: 20/01/2015; Published Date: 01/02/2015

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Abstract: The aim of this paper is modelling of three phase Brushless Dc Motor (BLDCM) using MATLAB .The performance of BLDC system is simulated. BLDC motors are gaining popularity rapidly now-a-days. BLDC motors are highly used in industries such as Aerospace, Appliances, Automotive, Consumer, Medical, Industrial, Automation Equipment and Instrumentation. BLDC motors do not use brushes for commutation, instead of that, they are electronically commutated. As compared to Brushed DC motor and Induction motor, BLDC motors have many advantages. Based on the mathematical model of BLDC motor, a control strategy of BLDC motor is proposed, then a simulation analysis is made using modern simulation software MATLAB/SIMULINK, which can provide accurate predictions of the system behaviour.

Keywords: BLDC, MATLAB/SIMULINK, control strategy, and simulation.

Corresponding Author: MS. RUTUJA A. BHAT

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How to Cite This Article:

Rutuja A. Bhat, IJPRET, 2015; Volume 3 (6): 122-132

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Available Online at www.ijpret.com 123 INTRODUCTION

A DC Motor is a device which is used to convert electrical energy into the mechanical energy. Number of electrical equipments is required to be supplied with kinetic energy for linear or rotating motion requirement.

BLDC motors are a type of synchronous motor. That means the magnetic field generated by the stator and the magnetic field generated by the rotor rotate at the same frequency. BLDC motors do not experience the” slip” that is normally seen in induction motors. BLDC motors come in single-phase, 2-phase and 3-phase configurations. Corresponding to its type, the stator has the same number of windings. Out of these, 3-phase motors are the most popular and widely used.

A motor that retains the characteristics of a dc motor eliminating the commutator and the brushes is called a Brushless DC motor. In many cases, Brushless DC (BLDC) motors can replace conventional DC motors. There are no brushes on the rotor. They are driven by dc voltage but current commutation is done by solid state switches that mean, the commutation is done electronically. The BLDC motors are available in many different power ratings ranging from very small motors as used in hard disks to large motors in (EV s) i.e. electric vehicles. [1] BLDC motors are highly used in industries such as Aerospace, Appliances, Automotive, Consumer, Medical, Industrial, Automation Equipment and Instrumentation since it has high reliability, high power density, low maintenance requirement, lower cost and lower weight. BLDC motors have many advantages over brushed DC motors. Some of these are:

 Higher efficiency

 Higher speed ranges

 Noiseless operation

 Better speed versus torque characteristics

 Long operating life

 Higher dynamic response

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Here, in this paper, we are employing SPWM technique

In this method the speed is controlled in a closed loop by measuring the actual speed of the motor. The error in the set speed and actual speed is calculated. A proportional plus integral (PI) controller is used to amplify the speed error and adjust the pwm duty cycle. [3]By analysing the motor speed, torque and other parameters and imposing different control algorithm on the system, a best strategy can be adopted. Lastly, here, in this paper, a simulation model of BLDC motor is built, based on mathematical analysis, the reliability and validity of this method has been proved by simulation results.[4]

2. TYPE OF CONTROL TECHNIQUES OF PMBLDC MOTOR.

There are various control techniques available for controlling PMBLDC motor. But basically two methods are available i.e. sensor control and sensorless control. Some design utilised both to provide high torque at high load and high efficiency at low load. Such a type of hybrid design allows the control of harmonic current. [5]

Various senseless methods for BLDC motors are analyzed in [6-10]. Modeling of BLDC is given in [3]. The speed control of brushless drive employing PWM technique using digital signal processor was proposed in [6]. A PSO based optimization of PID controller for a linear BLDC motor is given in [7-8].Speed Control of BLDC based on CMAC & PID controller is explained in [9]. Direct torque control and indirect flux control of BLDC motor with non-sinusoidal back emf method controls the torque directly and stator flux amplitude indirectly using d axis current to achieve a low-frequency torque ripple free control with maximum efficiency[10] ,[11]Proposes the simulation of brushless DC motor on SVPWM control.

This paper deals with the control strategy of using SPWM to control the system. An accurate model of complete system is required to control the system.

3. SIMULINK MODEL OF BLDC MOTOR

Here, we are considering two models: open loop model and the closed loop model with speed feedback of BLDC motor. In both the models, we are using six MOSFET s as a three phase inverter, to which the BLDC motor is connected. In case of closed loop structure, speed feedback is given to the pulse generator along with a reference speed of 1500 rpm. Here the pulses are generated. The error signal is given to the MOSFET switches and then these signals are passed over to the BLDC motor.

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Available Online at www.ijpret.com 125 Fig -3(a): Open loop model with no feedback

Closed loop model is shown below:

Fig -3(b): Closed loop model with feedback

4. SIMULATION RESULTS

Fig shows the simulation results with following parameters; R=0.1Ω, L=1 mH, M=0.5 mH, J=0.002kg.sq.m. Tl=0.5 Nm and simulation time = 0.5 s.

(i). Simulation results for open loop

For speed, angle theta and electromagnetic torque, the waveforms are;

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Voltage and current waveforms:

Fig -4(i) (d), (e): Output waveforms for voltage & current.

For open loop simulation model, the FFT analysis is given as:

For speed

Fig -4(i) f: FFT analysis for speed

For theta

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For electromagnetic Torque

Fig -4(i) h: FFT analysis for electromagnetic torque

For voltage

Fig -4(i) d: FFT analysis for voltage

For current

Fig -4(i) i: FFT analysis for current

(ii). Simulation results for closed loop

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Available Online at www.ijpret.com 128 Fig -4(ii) a: Output waveform for speed

For rotor angle theta

Fig -4(ii) b: Output waveform for theta

For electromagnetic torque

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For current

Fig -4(ii) d: Output waveform for current

For voltage

Fig -4(ii) e: Output waveform for voltage

For closed loop simulation model, FFT analysis is given as:

For speed:

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For theta:

Fig 4(ii) g: FFT analysis for thet

For electromagnetic torque:

Fig -4(ii) h: FFT analysis for electromagnetic torque

For voltage:

Fig -4(ii) i: FFT analysis for voltage

For current:

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Available Online at www.ijpret.com 131 5. CONCLUSION

The modeling procedure proposed here in this paper helps in simulation of various types of BLDC motors. The fruitful simulation results show that such a modeling is very useful in studying the drive system before taking of the dedicated controller design.

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