Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 ISSN: 2289-6260 © 2013 Academic Research Online Publisher. Review Paper Performance Analysis of Different Techniques for Pulse Width Modulation-A Survey Ehsan Neptune a,*, Seyed Mohammad Shariatmadar b, Behzad Moradi c a, b,c Islamic Azad University, Naragh Branch, Naragh, Iran * Corresponding author. Tel.:…….; E-mail address:ehsan.neptune.iaun@gmail.com Abstract Keywords: AC motors, pulse width modulation technique, SVPWM. Accepted:20 August2014 In industrial in order to apply energy requirements of motor, converters are used. Pulse Width Modulation technique is a suitable approach that increased in industrial application in last decades. The easy control and implement are the most advantage of PWM. In this paper survey of different techniques for PWM is presented. It is contain single pulse modulation, multiple pulse modulation, and space vector based PWM (SVPWM). In order to better understand the two last techniques are simulated and line voltage and line current of these techniques are presented in their relation part. © Academic Research Online Publisher. All rights reserved. 1. Introduction There are many methods to control output voltage but the best one is concatenate PWM In general, the machines are used to convert one kind of energy to another kind of energy. When the conversions take place from electrical to mechanical, the machine is motor. By this point AC motors are used to convert electrical energy to mechanical energy [1]. In control within inverter. One of the most popular methods that used to analog circuit control is PWM [4]. Pulse width modulation technique is used in many applications such as measurement and etc. PWM is a technique that controlled the width of pulse [5, 6]. industry, induction motors are widely used because of their advantage. Its advantage is The like as: 1. bootstrap, 2. no need for transmission the information by encoding maintenance, 3. low price, 4. simplicity and them, also its used to control the power that strength building [2, 3]. 157 | P a g e PWM technique can be used to Ehsan Neptune et al. / Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 applied to the electrical device, in other word advantage of this method. We have power loss it’s its main use. when there is voltage or current, so in this technique because of the Absence of voltage In last two decades many kinds of PWM technique have been studied [7]. or current, power loss is zero. The descriptions of PWM is contains the different kind of methods, concept and performance. There are many parameters that have effect on 2. PWM techniques their implementation ac drives, such as power In this part different kind of PWM technique is level and semiconductor device [8]. The presented. These different kinds are containing amount of average value of voltage or current single that applied to the load can be control by modulations, and Space Vector based PWM turning on and off the switch. This switch (SVPWM). pulse modulation, multiple pulse works at the fast speed. In general, the switching will be done several times in a 2.1. Single pulse width modulation minute and it’s different for each device. In a In this technique, in every half-cycle there is faint lamp it’s 120 Hz and for motor drive it’s just one pulse and width is depends on different from few kHz to tens of kHz. requirements of output voltage. As it’s clear Proportion of ‘on’ time to the interval time is from figure 1, by this technique the reference defined as duty cycle. The duty cycle has signal is converted to square wave signal. To direct proportion with power [9, 10]. obtain this square wave, the positive output Since the power loss in PWM technique is very low, it can be mentioned that is the best signal is related to the positive input and negative output is related to negative input [11, 12]. Fig. 1: Gating signal production of single PWM 158 | P a g e Ehsan Neptune et al. / Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 The switching waveform frequency of triangle is . By this frequency the speed of inverter switching (turning on and off) is controlled. To modulate the switch duty ratio, The control signal, frequency of , by the is used. This is the fundamental frequency of the inverter voltage output. Since the output of the inverter is affected by the switching frequency it will contain harmonics at the switching frequency [13]. The duty cycle of the one of the inverter switches is called the amplitude modulation ratio, 2.2. Multiple pulse width modulations In this technique the amount of harmonic is reduced by applying multiple pulses in each output voltage half cycle. Figure 2 shows the signal for turning on and turning off transistors. This signal is produced by comparing reference signal (with frequency) with triangular carrier wave (with as output frequency). Modulation index is varied from 0 to 1. By this variation, pulse be varied from 0 to ⁄ and follow of that, the output voltage variation is from 0 to . (1) [14]. Where: (2) Fig. 2: Gating signal production of multiple PWM 159 | P a g e as output (3) Ehsan Neptune et al. / Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 Line voltage and line current of multiple pulse and 4 respectively. width modulations are presented in figures 3 LINE VOLTAGE 800 600 LINE VOLTAGE(VOLT) 400 200 0 -200 -400 -600 -800 0 0.05 0.1 0.15 0.2 TIME(SECOND) 0.25 0.3 0.35 0.4 0.35 0.4 Fig. 3: Line voltage of multiple pulse width modulations LINE CURRENT 80 60 LINE CURRENT(AMP) 40 20 0 -20 -40 -60 0 0.05 0.1 0.15 0.2 TIME(SECOND) 0.25 0.3 Fig 4: Line current of multiple pulse width modulations 2.3. Space vector pulse width modulations In power conversion space vector pulse width modulation has essential and viable role. The 3. The THD is minimum in switching wave form 4. Its implementation is easy and its computational calculations is very low main goals of gate pulse generating SVPWM are as follow [15]: SVPWM is used to control the output voltage and input current. SVPWM technique is an 1. Wide linear range of modulation 2. Switching loss is minimum advantage since it increased the flexibility of switching. Under unbalanced conditions SVPWM can have useful advantage [16, 17]. 160 | P a g e Ehsan Neptune et al. / Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 Fig. 5: Circuit of three phase-voltage source inverter. To implement of SVPWM, voltage equation (4) can be transformed from abs frames to d-q reference frame. Equation 4and 5 shows its Where: relation. dq and ABC reference frame is showed in figure 6. [ ⁄ ⁄ ⁄ √ ⁄ √ ⁄ ⁄ ⁄ (5) ] And f can be voltage or current. Figure 7 shows the responds of line voltage for space vector pulse width modulations and the line current is presented in figure 8. Fig. 6: dq and ABC Reference Frame 161 | P a g e Ehsan Neptune et al. / Journal of Advanced & Applied Sciences (JAAS), 2 (5): 157-163, 2014 LINE VOLTAGE 800 600 LINE VOLTAGE(VOLT) 400 200 0 -200 -400 -600 -800 0 0.05 0.1 0.15 0.2 TIME(SECOND) 0.25 0.3 0.35 0.4 Fig. 7: .line voltage of space vector pulse width modulations LINE CURRENT 60 40 LINE CURRENT(AMP) 20 0 -20 -40 -60 -80 0 0.05 0.1 0.15 0.2 TIME(SECOND) 0.25 0.3 0.35 0.4 Fig. 8: .line current of space vector pulse width modulations the quality is better, total harmonic distortion 3. Conclusion (THD) is lesser and torque ripple is reduced. There are many methods to control output voltage but the best one is concatenate PWM control within inverter. By proportion switching and applying fixed dc voltage to inverter, ac output voltage will be produced. Pulse Width Modulation technique is a suitable approach that increased in industrial application in last decades. The easy control and implement are the most advantage of PWM. 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