Pv power system based mppt z source inverter to supply bldc motor

1Dept. of EEE MCET

PV Power System Based MPPT Z-Source Inverter to Supply a

Sensorless BLDC Motor

Guide, Submitted by,Mr. Manu N Govind Renjith Chandran NairAsst: Prof Dept of EEE S7 EEE,MCET PTA Roll No:4431

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• The solar energy as PV power systems can be operated as a stand-alone, hybrid or grid connected systems.

• Photovoltaic (PV) water pumping systems have been increasingly popular in remote areas where grid is not accessible or is too costly to install.

• PV pumps are already in use in several parts of the world. But they suffer from maintenance problems due to brushes and commutator .

• The problems can be overcome by choosing BLDC motor.

Introduction

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CONTENTS• Photovoltaic System• Conventional PV water pumping system• Maximum Power Point Tracking(MPPT)• ZSI• BLDC motor

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Description Of The Components

PV cell

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BLDC MOTOR

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• A BLDC motor is a rotating electric machine where the stator is a classic three phase stator like that of an induction motor and the rotor has surface mounted permanent magnets.

• Also called brushless Permanent Magnet DC (BLDC) or synchronous DC motor

• The construction of modern brushless motors is very similar to the ac motor, known as the permanent magnet synchronous motor.

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Z-Source Inverter

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• Z-source inverter (ZSI), which is based on Z-source network .It can be used to buck and boost the output AC voltage, which is not possible using traditional voltage source or current source inverters.

• Figure shows a topology of the single phase Z-source inverter.

• The impedance network is placed between the power source and the single phase inverter.

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Sensorless BLDC motor driven by 3 Phase ZSI

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• The maximum power of PV array is extracted by MPPT control method and then is fed to the sensor less BLDC motor.

• PV power varies to different environment conditions.

• The sensor less BLDC motor should be driven by variable reference speed. In order to achieve the reference speed for sensor less BLDC motor, the input voltage of inverter is regulated at a constant value (Vinref=300V).

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Equivalent circuit of PV solar cell

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• Figure illustrate the nonlinear variations of the PV maximum power point respect to irradiation levels.

• The voltage and current of a PV array vary in respect to insolation and temperature levels, the equation has been computed for several insolation levels

• In this paper PV system is modelled in the PSCAD program as a DC voltage source based on equation.

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Output Characteristics of PV module

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BLDC MOTOR DRIVE• Permanent magnet DC motors use mechanical commutator

and brushes to achieve the commutation.• It has rotor and stator• BLDC motors use permanent magnets instead of coils in the

armature and so do not need brushes.• It has hall effect sensors.• Sensor detects the rotor position by incremental encoder then

it is removed.

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Back EMF patternand reference current

generation

• va, vb, vc- phase voltages.

• ia, ib, ic-phase currents.

• ea, eb, ec-phase back EMF waveforms.

• R-phase resistance.

• L-self inductance of each phase.

• M-mutual inductance between any two phases

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• VC1 and VC2-capacitors voltages

• B is the boost factor of ZSI.

• Vd and VO- input and output

• voltages of impedance network.

OPERATION PRINCIPLES

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CONTROL SYSTEM DESCRIPTION

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• Fig. describes the basic building blocks of PV array MPPT control and the sensorless BLDC motor drive.

• The drive system consists of the PI speed controller, reference current generator, hysteresis current controller, three-phase ZSI and the motor-load unit.

• First the reference voltage of PV array is determined by the IC MPPT controller and compared with the PV array voltage.

• The motor currents are compared with the reference currents and the hysteresis current controller regulates the winding currents (ia, ib, ic) within the small band around the reference currents. These switching commands and the Z-Source switching commands are ORed to drive inverter switches.

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SIMULATION RESULTS• The proposed system was simulated by PSCAD/EMTDC to

evaluate the system capability in response to different operation conditions.

• It has three different operating conditions.

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ADVANTAGES

• Less power switches.• Smaller capacitance.• Smaller inductance.• Fast dynamic response

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CONCLUSION• This paper proposes a sensor less BLDC motor supplied by PV

array based on ZSI.• Conventional PV systems needing two stages of power

converters the proposed system has employed just a three phase ZSI extracting the maximum power of PV array and driving a sensor less BLDC motor simultaneously for different operation conditions.

• Less power losses, rapid tracking of MPPT and low electromagnetic torque ripple, demonstrating high current control capability.

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REFERENCES1. M. G. Jabori, “A contribution to the simulation and design

optimization of photovoltaic systems,” IEEE Trans. on EC, vol. 6, no.3, 1991, pp. 401-406.

2. J. Samin and et al, “optimal sizing of Photovoltaic Systems in Varied Climates,” Elsevier , Solar Energy, vol. 6, No. 2, 1997, pp.97-107.

3. Z. Zinge, “Optimum Operation of a Combined System of a Solar Cell Array and a DC Motor,” IEEE Trans. on PAS, vol. pas-100, no. 3, 1981,pp. 1193-1197.

4. F. Z. Peng, ‘‘Z-source inverter,’’ IEEE Trans. Ind. Appl., vol. 39, no. 2,pp.504-510, Mar.-April. 2003.