International Journal of Advance Engineering and Research Development

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1 Scientific Journal of Impact Factor (SJIF): 4.14 International Journal of Advance Engineering and Research Development Volume 3, Issue 10, October e-issn (O): p-issn (P): Single Phase to Three Phase System Using Dual Boost Converter to Drive Induction Motor Along With Active Power Factor Correction Technique Yuvraj U. Rathod 1, Mrs. M. R. Bachawad 2 1 M.E student, Electrical engineering department, Government College of engineering, Aurangabad, India. 2 Associate Professor, Electrical engineering department, Government College of engineering, Aurangabad, India. Abstract This paper offerings a single-phase to three-phase drive system composed of dual boost converter, three phase PWM inverter plus an Induction motor. It gives comparisons between boost and dual boost converter topology. The proposed system permits enhancements of power factor and sinusoidal input current at the terminal of single phase source by using current control mode with speed control of three phase induction motor using v/f method. Such a single phase to three phase conversion technique has large range of application from rural area to industrial area where three phase machines work easily on available single phase suppl. Finally a MATLAB simulation based model is developed for single phase to three phase system and simulation results are present Keywords- Average current control mode, Boost converter, Dual boost converter, Induction motor, Power factor, Rectifier, THD, SPWM I. INTRODUCTION Traditionally, conversion of single phase to three phase system conversion has been done by various ways of switching processes with the help of power electronics devices. It is somewhat common to have only a single phase power grid in domestic, commercial, manufacturing, and mainly in urban regions; however the variable speed drives may entreaty a three phase power grid. Single-phase to three-phase AC to DC to AC conversion usually employs a full bridge topology, which implicates many power switches, such a converter is represented here as conventional topology. As conversion system includes various stages of conversion processes that defines distortion and generate harmonics on source line and load in system hence the input power factor become poor [1]. Now development in technologies causes various power factor improvement techniques are employed to overcome these power quality problems some of which the boost converter topology has been extensively used in various conversion applications [2]. Such that now a days AC to DC power supplies with power-factor correction (PFC) techniques is almost entirely implemented with boost topology, usually boost topology does not provide permissible value of higher power factor. So to overcome this problem, Dual Boost converter technique can be employed to overcome the performance of input characteristic of current and used to improve input power factor and reduces distortion in input current waveform. [3]. In this paper, a singlephase to three-phase drive system composed of single-phase rectifiers along with dual boost converter to give boost output to three phase inverter to drive three phase induction motor along with speed control by using V/F method is proposed. The proposed system is perceived to operate where the single-phase utility grid is the unique option available. As Compared to the conventional topology, the proposed system permits to reduce distortion in input currents and the total harmonic distortion (THD) of the system to increase fault tolerance of the system II. PROPOSED SYSTEM AND BLOCK DIAGRAM The block diagram showing schematic arrangement of single phase to three phase converter using dual boost topology to drive induction motor Fig. 1 Block diagram of implemented All rights Reserved 116

2 Here, schematic arrangement of proposed technique can be divided into two parts such as source of AC link to DC link conversion and DC link to AC link conversion. So Part 1 composed of an input supply along with line filter to reduce input harmonics and to make superior input current waveform, a single-phase uncontrolled diode rectifier is used here to convert AC link into DC link, to increase output of AC/DC converter dual boost topology is used with an active power factor correction stage using the principle of current control mode technique to maintain power factor up to unity. Also Part 2 consisting Sinusoidal PWM inverter to convert DC into AC three phase links along with constant V/F topology to control speed of three phase induction motor using V/F speed control technique [1], [2], [3] 3.1 Boost topology III. DEVELOPMENT OF PROPOSED SYSTEM The part of converter consisting of boost chopper termed as Boos converter. Generally boost topology served two functions such as 1) it controls the line current to be sinusoidal at unity power factor and 2) boost converter is needed to efficiently convert DC voltage from lower level to higher level [5] As to reduce losses and converter output is depend on duty cycle their relations are as follows V o Vs ( 1 D) t D T The peak to peak ripple current of inductor L is given as on (1) (2) Vs( Vo Vs) I (3) flva The peak to peak ripple voltage of capacitor is given as Io( Vo Vs) Vc (4) VofC The value of inductance respectively the capacitance C of converter are calculated at the boundary operation condition of the circuit as fallows ( 1 D) DR L (5) 2 f D C (6) 2 fr 3.2 Principal of control A dc-dc converter must provide a regulated output voltage DC link under variable load and input voltage conditions. The converter component values are also varying with temperature, time and pressure. Hence, the control of the output voltage should be performed in a closed-loop mode using principles of negative feedback system. The two most common closed-loop control methods for PWM dc-dc converters, namely, the voltage-mode control and the current-mode [2], [3], [5] Voltage Mode Control In this control mode converter technique output voltage of system is controlled and feedback through a resistive voltage divider. It is compared in a voltage error amplifier with a precision external reference voltage (V ref). The error amplifier produces a control voltage that is compared with constant amplitude of saw tooth waveform. The comparator or the PWM Modulator produces a PWM signal that is fed to controlled switches, which is in the dc-dc converter. The duty ratio of the PWM signal depends on the value of the control voltage [2], [3], All rights Reserved 117

3 3.2.2 Current Mode Control Fig. 2 principal of voltage mode control Main objective of this implemented scheme is intensive on Current Mode Control. In this mode of control as shown in fig., That Signals in current waveform has benefit over voltage signals. Voltage being gathering of flux, which is then slow in time as far as control strategy, is concerned, this led to the development of a new expanse in switch mode power supply scheme using mode of current Control. Hence, the average or peak current is employed in the feedback system of the switch mode power converters. It has given new possibilities of analysis and at same time introduced complexities in terms of multiple loops. [2], [3], [5] Fig. 3 Principal of current mode control 3.3 Single phase rectifier circuit with boost topology In this implemented scheme, the converter consist of uncontrolled diode rectifier is coupled with boost chopper which is eighter of boost type or dual boost type converter Single phase rectifier circuit with boost converter The main principle that energies the boost converter is the tendency of an inductor to resist changes in current, when being charged it act as a load and absorbs energy as like a resistor. When being discharged it acts as energy source as like a battery. The voltage is creates during the discharge phase is depend on the rate at which change of current and also not on the original charging voltage, thus allowing different input and output All rights Reserved 118

4 Fig. 4 boost converter Fig. 5 On and Off states of a boost rectifier The input current i(t) is controlled by changing the conduction state of transistor. As transistor is in switching mode by applying suitable firing pulse sequence, hence the waveform of the source side current can be controlled to follow a sinusoidal reference which can be observed in the positive half wave. The ON and OFF state of switching periods of the transistor generates an increase and decrease in the inductor current I L [1], [2], [3] Fig. 6 THD of system using Boost topology (THD=10.71%) As, it can be clearly seen from fig that the higher order harmonics are significantly lowered in the line current by using a boost converter [1], All rights Reserved 119

5 Fig. 7 Power Factor of system using Boost topology (P.F=0.989) In case of boost converter due to its simplified structure it is more capable for the power applications of low to medium range. However, it has a very slow dynamic response and power factor correction. [3] Single phase rectifier circuit with dual boost converter To avoid low dynamic response and power factor correction issue, two converters can be connected in Parallel to form the parallel PFC scheme i.e. dual boost converter. In case of above proposed system power from the ac source to load flows through two parallel paths. The main path is a rectifier, in which power is not managed double for PFC, whereas the other path processes the input power twice for PFC purpose. To achieve both output voltage regulation and unity power factor, only the difference is, there is need to process dually between the input power and output power. Hence, high efficiency can be obtained by this technique Fig. 8 Dual Boost converter Here, we use a parallel scheme, in that choke (L b1) and switch (T b1) are for main PFC while choke (L b2) and switch (T b2) are for active filtering. The filtering circuit aids two purposes i.e. it not only improves the quality of line current but also reduces the PFC total switching loss. The decrease in switching losses arises due to variable values of switching frequency and current amplitude for the mode of two switches. The comparable connection of switch mode converter is a well acknowledged strategy. It involves phase shifting of two or more boost converters operating at the same witching frequency which is connected in parallel All rights Reserved 120

6 Fig. 9 THD of system using Boost topology (THD=8.91%) Fig. 10 Power Factor of system using Boost topology (P.F=0.992%) 3.4 Inverter Circuit Topology Inverter circuit is used for converting the DC quantity into the AC quantity. In proposed technique three phase SPWM inverter, is used to convert DC output of dual boost converter into three phase AC voltage for the speed control of three phase induction motor using V/F method. Here an SPWM controller is used to drive the gate of the switches used in the inverter. By proper switching and control technique, inverter generates required voltage or frequencies. There are single phase and three phase inverters but the three-phase inverters are more regularly used in high power applications. This inverter consists of three half-bridge units; the switching devices can be IGBTs, BJTs, and GTOs. Fig shows the inverter circuit. The controlling of switches depends on the required frequency and desired power. When upper switch is turned on the corresponding lower switch should turn off and vice All rights Reserved 121

7 Fig. 11 PWM Simulink In case of 3-ph inverters of six modes of operation gating pulses are delayed by 120 degrees are possible for each cycle and has interval of 60 degrees. Therefore 3-ph voltages lag behind by phase shift of 120 degrees. The inverter output is a square waveform when it is not connected to a load and such a square shape waveform can be converted into sine waveform by using LC low pass filter [4] SPWM Controlled Technique In case of PWM mechanism topology, the output voltage is controlled by varying the width of pulses, if there are P-pulse per half cycle, the maximum pulse width is π/p. It is possible to choose the width of pulses in such way that certain harmonics could be eliminated. There are many methods of obtaining pulse with different widths. The most common one technique is the sinusoidal pulse-width modulation (SPWM) topology. In this technique, the pulse width are generated by comparing a triangular voltage V r of amplitude A, and frequency fr with a carrier half sinusoidal voltage V c of variable amplitude Ac and frequency of f s [4] Fig. 12 SPWM Controlled Technique Here, above figure shows control strategy the reference wave is compared with the carrier wave so the gate pulse is generated after the comparator operation. The output of comparator is fed to the Arm 1 of bridge inverter. Fig. 13 PWM carrier wave comparison Figure 13 shows the waveform of signal obtain from SPWM achieved by Matlab/Simulink model and respective gate pulse. The Amplitude modulation index is defined All rights Reserved 122

8 Vm M a Vcr (7) Where, V m - peak amplitude of the reference voltage waveform V cr - peak amplitude of the triangular voltage waveform The output voltage is controlled by changing the modulation index M from 0 to Induction Motor drive Induction motor is an electrical to mechanical conservation device and it is an asynchronous AC machine because the rotor speed is always less than stator magnetic speed. The construction of IM is rugged. Hence, Induction motors are the most commonly used due to their reliability, low cost and robustness. However, induction motors do not integrally have the ability of variable speed operation. Due to this reason, earlier dc motors were applied in most of the electrical drive system, But the recent developments in speed control methods of the induction motor have led to the place where in large scale use in almost all electrical drives application. [1], [5]. Out of the several methods of speed control of an induction such as frequency variation, variable rotor resistance pole changing, variable stator voltage, slip recovery method, constant V/f control, etc. the closed loop constant V/f control speed techniques most commonly used. In this method, By applying V/f ratio constant which in turn maintaining the maximum torque remains unchanged by taking the magnetizing flux constant. Thus, the motor is completely utilized in this method. Hence it is widely used in much application like in elevator, water pumping system and in industry [1], [5] IV. SIMULATION RESULTS AND DISCUSSION This paper involves simulation of Single Phase To Three Phase System Using Dual Boost Converter To Drive Induction Motor Along With Active Power Factor Correction Technique circuits and the analysis of the current and voltage waveforms. It starts with simple circuits with a gradual increase in complexity by initialization of new constituents and their consequent effect on the current and voltage waveforms. In this proposed technique we focused on the moto of improving the input current waveform i.e. making it sinusoidal by tuning the circuits along with maintaining power factor unity and then with the help of SPWM circuit converter DC dual boost DC link into three phase AC link to drive induction motor along with their speed control using V/F method. All the simulation work is done in MATLAB Simulink simulation of proposed conversion system Fig. 14 system model using MATLAB Simulink The proposed system shown in figure 14 is designed and simulated with the help of tool i.e. MATLAB. In that it consisting of various stages involving AC- to DC link conversion with the help of uncontrolled rectifier and then feed it into Dual boost topology where the DC link become boosted from lower voltage to higher level and is given to then PWM inverter. Here Boosted DC link to AC link is done and it given to induction motor for speed control using V/F All rights Reserved 123

9 4.1 simulation Single phase rectifier circuit with dual boost converter Here, two converters can be connected in Parallel to avoid low dynamic response and power factor correction issue, hence form the parallel PFC scheme i.e. dual boost converter. Here, power from the source of AC to the load flows through bi-parallel lanes. The main path is a rectifier, in which power is not handled dually for PFC, whereas the other path possess the input power dually boosted for PFC purpose, to achieve both output voltage regulation and unity power factor. Simulation result showed in figure 15, 16 & 17 consisting of source waveform along with power factor and output of dual boost converter. Fig. 15 sinusoidal waveform of input current and voltage Fig. 16 waveform of power All rights Reserved 124

10 Fig. 17 waveform of output of dual boost converter 4.2 Inverter Circuit Topology Inverter circuit is used for converting the DC quantity into the AC quantity. In this proposed technique three phase SPWM inverter is used to convert DC output of dual boost converter into three phase AC voltage for the speed control of three phase induction motor using V/F technique. Simulation result shown in following graph consisting of output of SPWM and rotor speed of three phase induction motor Fig. 18 waveform of three phase current of PWM Fig. 19 waveform of three phase voltage of All rights Reserved 125

11 Fig. 20 waveform of rotor speed of three phase induction motor 4.5 Analysis of power factor and thd along with output of boost topology Sr. No. Circuit topology Power factor THD Output Voltage 1 Boost Converter Dual Boost Converter Table 1.analysist of P.F, THD & output voltage 4.6 Analysis of speed control of i.m. using v/f topology Sr. No. Frequency(Hz) Speed (rpm) 1 30 Hz rpm 2 40 Hz 1198 rpm 3 50 Hz 1493 rpm Table 2.analysist of frequency & speed 4.7 APPENDIX Boost converter specification Inductor=0.230H, Capacitor=1.85 µf Three phase induction motor specification 1 H.P, 400V, 50Hz, 4 pole, 1440 rpm Stator & rotor resistance =2Ω & 1.9 Ω Stator & rotor inductance = H, Mutual inductance= Momentof inertia=0.02 kg.m2 Table 3 parameters of system V. CONCLUSION In this paper The Power Factor Correction with different converters are simulated with MATLAB Simulink. Paper shown and discussed on result of Boost converter using Current Mode Control and Dual Boost Converter using Current Mode Control technique, it is noticed that the Power Factor is better for Dual Boost Converter Circuit. Also it is noticed that THD is less for Dual Boost Converter. Here output of dual boost converter fed to SPWM inverter further is utilised to drive Induction motor to speed control. In constant V/F control topology, with the help of PWM inverter, we can vary the supply voltage as well as frequency such that the ratio V/F remains constant so that the flux remains same. So we can get different operating zone for various speeds and torques and also we can get various synchronous speeds with almost same maximum torque. Thus the motor is completely utilized and also we have a good range of speed All rights Reserved 126

12 REFERENCES [1] Pradeep M Patil, Sanjay L Kurkute, Speed control of three phase induction motor using single phase supply along with active power factor correction, ACSE Journal, Volume (6), Issue (3), Oct., 2006 [2] Sudhakar babu, Dr.G. V. Siva Krishna Rao, Simulation of Active power factor correction using boost type converter IJSETR Journal, volume 3, issue 10, October 2014 [3] P.Vijaya Prasuna, J.V.G. Rama Rao, Ch. M. Lakshmi, Improvement in Power Factor & THD Using Dual Boost Converter, IJERA journal, Vol. 2, Issue4, July-August 2012, pp [4] Mohammad H Rashid, power electronics Handbook (Academic press, 2001). [5] Bimal K. Bose, Modern power electronics and AC drives, All rights Reserved 127