Design of PV- based Impedance Source Inverter fed Squirrel Cage … · 2018-06-19 · inverter (ZSI) fed Squirrel Cage Induction Motor (SCIM) drive. In this work, with the implementation

October 2017, Volume 4, Issue 10 JETIR (ISSN-2349-5162)

JETIR1710055 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 332

Design of PV- based Impedance Source Inverter fed

Squirrel Cage Induction Motor Drive Suhashini Shinde*1

*1Department of Electrical Engineering, C.U.K-585367, Karnataka, India

Abstract— This paper presents a MATLAB / Simulink based design and performance of photo voltaic (PV) - based Impedance (Z)-source

inverter (ZSI) fed Squirrel Cage Induction Motor (SCIM) drive. In this work, with the implementation of Z link to the PV-source system, there

is no requirement of additional maximum power point tracking (MPPT) unit. The parameters of Z-source inverter are determined for boost

control method for a fixed modulation index. A simple MOSFET/Diode based universal bridge has considered as inverter along with the

impedance (Z) link of the ZSI. Performance of PV based ZSI is verified by connecting a constant speed squirrel cage induction motor drive

as a load.

Index Terms— Photo voltaic (PV), impedance source inverter (ZSI), maximum power point tracking (MPPT), total harmonics

reduction (THD), Squirrel Cage Induction Motor (SCIM), torque, speed.

________________________________________________________________________________________________________

I. INTRODUCTION

Among the renewable energy sources, photovoltaic (PV) systems are more popular because of simplicity in installation, easy

maintenance, noiseless, eco-friendly etc… Due to low cost of renewable energy sources, PV systems have given a lot of importance

in many applications [1].

One of the recent developed inverter topologies is Impedance (Z) source inverter (ZSI). The ZSI is very advantageous over

traditional inverters and it can be adapted for both in all ac and dc power conversion applications. [2]-[3]. Advantages of ZSIs in

electrical applications have given in literature [4],[5]. For boosting the dc link voltage of ZSI utilizes shoot through state. The r.m.s

value of output fundamental component of line voltage of ZSI can be expressed by given equations (1)-(3)[7]-[9]

𝑉𝑟𝑚𝑠 = 0.612 𝑀𝐵𝑉𝑑𝑐 (1)

Boost factor is a function of M is given by

𝐵 =1

2 𝑀− 1 (2)

And Modulation index (M) is given by

𝑀 = 1 − 𝐷 (3)

Where “D” is the shoot through ratio.

Shoot through is employed by comparing dc reference line signal with sinusoidal signal. Maximum possible value of shoot

through ratio, D of boost control is limited to (1-M). Hence for lower value of M, shoot through ratio is high which results in

degradation of spectral performance and vice-versa. In series ZSI, LC-network and Inverter Bridge both are in series manner. This

series combination is connected across dc source, which shows the reduced voltage across both capacitors [7]-[9].

Rest of the paper is organized as fallows. In introduction, importance of renewable energy based systems, PV systems

feasibilities, ZSI and its advantages, designing factors are briefly discussed. Proposed PV- based ZSI fed squirrel cage induction

motor drive system design and modelling in MATLB/Simulink gui environment are given in section. II Simulation results and

discussion are given in section.III. Finally conclusion and future scope of the proposed system is given in section. IV.

II. MODELLING AND DESIGN OF PROPOSED PV-BASED ZSI FED SQUIRREL CAGE INDUCTION MOTOR DRIVE SYSTEM

Fig.1. shows the proposed PV- based ZSI fed Squirrel Cage Induction Motor Drive system. PV-array is the source of the proposed

system. Without need of an additional MPPT unit, ZSI provides an effective single-stage dc-ac power conversion with buck-boost

capability, which further reduces the volume of overall system, reduces the cost of the system, reduces the THD value and increases

the efficiency.

PV- Array System Design Aspects

Fig.2. shows the well-known single diode equivalent circuit model of a photovoltaic cell [10]. Specifications of considered 1KW

PV system are given by Table. I .The I-V characteristics of PV-systems is given by equations (4),(5) [11].

𝐼𝐷 = 𝐼𝑂 (𝑒𝑞(𝑉+𝐼𝑅𝑆)

𝐾𝑇 − 1) (4)

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𝐼 = 𝐼𝐿 − 𝐼𝑂 (𝑒𝑞(𝑉+𝐼𝑅𝑆)

𝐾𝑇 − 1) −𝑉+𝐼𝑅𝑆

𝑅𝑆ℎ (5)

Where,

𝐼𝐷 = Diode Current (A)

𝐼𝑂 =Diode saturation current (A)

𝑞 = Electron charge (Jouls)

𝐼𝐿 = Generated light current (A)

𝐾 = Boltzman constant (J/K)

𝑇 = Temperature (K)

𝑉 = Output voltage (V)

Fig.1. PV- based ZSI fed Squirrel Cage Induction Motor Drive System

Fig.2. DC Equivalent Circuit of PV-Cell

Inductor (L) and Capacitor Design of ZSI

The fallowing equations are used for designing the LC elements [12]. The specification of the ZSI system is given by Table. II .

All the designing the equations of ZSI is given by equations (6)-(13) [11]-[15].

𝐶 =𝐼𝐿∙𝑇0

𝑉𝑃𝑉 (6)

𝐿 =𝑉𝑑𝑐∙𝑇0

∆𝐼 (7)

Shoot Through Duty Ratio

𝑇0

𝑇= 1 −

√3𝑀

2 (8)

Boost Factor




𝐵 =1

1 −2𝑇0

𝑇

=1

√3𝑀 − 1 (9)

Inverter Gain or Voltage Gain of Inverter

𝐺 =𝑉𝑎𝑐𝑝

𝑉𝑑𝑐2⁄

= 𝑀 ∙ 𝐵 =𝑀

√3𝑀 − 1 (10)

Peak AC output Voltage

𝑉𝑎𝑐𝑝 = 𝑀 ∙ 𝐵 ∙𝑉𝑑𝑐

2⁄ (11)

Peak DC link Voltage

𝑉𝑑𝑐𝑙 = 𝐵 ∙ 𝑉𝑑𝑐 (12)

Buck Boost Factor

𝐵𝐵 = 𝑀 ∙ 𝐵 (13)

Where,

T0 – On Time

T – Total time for a cycle

TABLE I

SPECIFICATIONS OF THE CONSIDERED 1KW PV SYSTEM

Sl. No Name of the parameter Rating of the parameter

1 PV Panel Sun Power SPR 350 WHT

2 Power 1kW

3 No. of cells per Module 96

4 No. of series connected modules 3

5 No. of parallel connected

modules

1

6 Voc 𝑉𝑜𝑐 64.2 V

7 𝐼𝑠𝑐 5.96 A

8 𝑉𝑚𝑝𝑝 54.7 V

9 𝐼𝑚𝑝𝑝 5.58 A

10 𝑅𝑠𝑒𝑟𝑖𝑒𝑠 0.037998 Ohms

11 𝑅𝑝𝑎𝑟𝑎𝑙𝑙𝑒𝑙 993.51

12 𝐼𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑖𝑜𝑛 1.1753e-8

13 Diode Quality Factor 1.3

14 Irradiance 1000 W/m2

15 Cell Temperature 25oC

Load Specifications of Constant Speed Squirrel Cage Induction Motor

In this work, a constant speed Squirrel Cage Induction Motor (SCIM) drive is considered as a load. The specification of the load

system is given by Table.III




TABLE II

SPECIFICATIONS OF THE ZSI


1 Modulating Index (M) 0.8

2 DC link voltage (Vdc) 188 V

3

Shoot Through Duty Ratio

0.308

4 Boost Factor 2.593

5 Peak DC Link Voltage 487 V

6 Buck Boost Factor 2.075

7 Gain of Inverter 2.075

8 Carrier Frequency 10kHz

9 Reference Signal Frequency 50Hz

10 Inductor (L) 4mH

11 Capacitor (C) 188 V

TABLE III

SPECIFICATIONS OF THE SCIM DRIVE


1 Machine Type Induction Machine

2 Rotor Type Squirrel Cage

3 Power 1KW

4 Frequency 50Hz

5 Speed 157 rad/s or 1500rpm

6 Pole Pairs 2

III. MATLAB/SIMULINK BASED RESULTS OF PROPOSED SYSTEM

This section shows the MATLAB/Simulink based designed proposed system simulation results. The designed PV based ZSI is

fed to a constant speed SCIM drive.

Fig.2. shows the MATLAB/Simulink based I-V Characteristics of considered 1 kW PV system. Fig.2.shows the

MATLAB/Simulink based P-V Characteristics of considered 1 kW PV system. Fig.4. shows the MATLAB/Simulink based DC

link voltage of proposed system. Fig.5. shows the MATLAB/Simulink based 3-phase input voltage waveform to 3-phase constant

speed SCIM drive of proposed PV based ZSI system. Fig.6. shows the MATLAB/Simulink based speed of SCIM drive of proposed

PV based ZSI system. Fig.7. shows the MATLAB/Simulink based torque of SCIM drive of proposed PV based ZSI system.

Fig.2. MATLAB/Simulink based resultant wave form of I-V characteristics of 1 kW PV system




Fig.3. MATLAB/Simulink based resultant wave form of P-V characteristics of 1 kW PV system

Fig.4. MATLAB/Simulink based DC link voltage of proposed system.

Fig.5. MATLAB/Simulink based 3-phase input voltage waveform to 3-phase constant speed SCIM drive of proposed system

Fig.6.MATLAB/Simulink based speed response of SCIM drive of proposed PV based ZSI system.




Fig.7. MATLAB/Simulink based torque response of SCIM drive of proposed PV based ZSI

CONCLUSION

Thus, in this paper design, modelling and control of constant speed squirrel cage induction motor (SCIM) driven by PV based

ZSI have done in MATLAB/Simulink gui environment for small scale rating applications. The simulation results prove that the

developed PV based ZSI tracks the maximum power throughout the operation without introducing a MPPT unit from outside. The

control strategy of the SCIM drive is in the acceptable range. For further research on PV based ZSI fed SCIM drive , a closed loop

control , for more reliability some more renewable energy sources , for more accuracy Artificial Intelligence (AI) based Artificial

Neural Networks (ANN) control schemes can be implemented.

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Design of PV- based Impedance Source Inverter fed Squirrel Cage … · 2018-06-19 · inverter (ZSI) fed Squirrel Cage Induction Motor (SCIM) drive. In this work, with the implementation