27-04-2011, 09:27 AM
Electrical seminar.PPT (Size: 665 KB / Downloads: 226)
IMPEDENCE - SOURCE INVERTER FOR MOTOR DRIVES
Traditional Source Inverters
Voltage Source Inverter.
Current Source Inverter.
Voltage Source Inverter
Problems
This inverter can be used only for Buck operation.
For application where the required output voltage is high, an additional dc-dc boost converter is needed to obtain a desired ac output.
This inverter does not have ability to provide ride-through during voltage sags .
additional power converter stage increases system cost and lowers efficiency.
It is immune to EMI noise.
Current Source Inverter
Problems
This Inverter can be used for only Boost operation.
The dc link Filter Inductor is large, costly and Contributes to losses
The open circuit by EMI noise is the major concern
Can cause high voltage spikes on motor terminals.
Usually not possible to use with more than one motor.
Lower efficiency due to high power loss
FEATURES OF Z – SOURCE INVERTER
The impedance source inverter can provide Buck-Boost operation.
The output voltage range is not limited.
It is less effected by EMI noise.
This Inverter provide ride-through during voltage sags
It reduces the harmonics therefore increase the power factor and efficiency.
The impedance source inverter cost is low.
The impedance source inverter concept can be applied in all ac-ac , dc-dc, ac-dc, dc-ac power conversion
Proposed Z-Source Inverter Unit
Block Diagram –Impedance Source Inverter for A.C Drives
Application
Variable Speed Drives
For Fuel Cells in motor vehicles.
Variable speed drives.
Uninterruptible power supplies.
Induction heating.
High voltage dc transmission lines
The impedance source concept can be applied in all ac-ac , dc-dc, ac-dc, dc-ac power conversion