It's about motor drive

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Presented by:
Md. Mustafa Zaved
Department of Electrical and Electronic Engineering
International Islamic University Chittagong
A Comparative Analysis Among PWM Control Z-source Inverter
with Conventional PWM Inverter for Induction Motor Drive
Md. Khurshedul Islam, Md. Mustafa Zaved, Air Mohammad Siddiky
and Khandakar Abdulla Al Mamun

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Why Inverter for Induction Motor?
• In the last century DC motor widely used in the industries for variable
speed application.
• In that times induction motor only used for constant speed application due
to unavailability of variable frequency voltage supply.
• But now days, with the development of power electronics, it has made
possible to supply variable frequency voltage
• Due to the availability of variable frequency voltage, induction motor has
taken the workhorse of the industry because of its robustness, less
maintenance, high efficiency & low cost
• There are basically two ways to obtain variable frequency voltage
1. Cycloconverter
2. Inverting Process
• Cycloconverter is suitable for large applications, such as locomotives and
cement mills
• Inverting process is very much suitable for small & medium application
• PWM technique is widely used to vary both frequency & voltage

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Conventional Inverters for Motor Drive
On the Basis of AC output waveform, conventional inverters are two types
1. Current Source Inverter
2. Voltage Source Inverter
Fig2: Basic Circuit Diagram of Conventional VSIFig1: Basic Circuit Diagram of Conventional CSI
Limitations of CSI:
• Boost Converter
• Possibility of miss gating
• Contains more harmonics
• Slower dynamic response
Limitations of VSI:
• Buck Converter
• Possibility of miss gating
• Also contains some harmonics
• Required additional boost converter

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Z-Source Inverters for Motor Drive
Advantages of ZSI:
• The Source either be voltage or
current source
• Provides buck-boost capability
• Contains lower harmonics and EMI
noise than conventional
Fig: Basic Circuit Diagram of Z-source Inverter

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Circuitry Arrangement
Fig1 : Simulation circuit arrangement of CSI for Motor Drive Fig2 : Simulation circuit arrangement of VSI for Motor Drive
Fig3 : Simulation circuit arrangement of VSI for Motor Drive

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Comparison of Rotor Speed
Drive
Torque
CSI VSI ZSI
0 N-m
4 N-m
7 N-m

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Comparison of Electromagnetic Torque
Drive
Torque
CSI VSI ZSI
0 N-m
4 N-m
7 N-m

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Comparison of Rotor Current
Drive
Torque
CSI VSI ZSI
0 N-m
4 N-m
7 N-m

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Comparison of Stator Current
Drive
Torque
CSI VSI ZSI
0 N-m
4 N-m
7 N-m

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Conclusion
• This paper focus on a comparative analysis of conventional
and Z-source inverter for motor drive.
• Z- source fed induction motor provides high starting torque
• Quicker operation
• Reduces the settling time of rotor and stator currents as
compared to CSI and VSI fed IM.

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