14-12-2012, 05:36 PM
Power Electronic Devices
Power Electronic.ppt (Size: 1.04 MB / Downloads: 111)
An introductory overview of power electronic devices
The concept and features
Power electronic devices: are the electronic devices that can be directly used in the power processing circuits to convert or control electric power.
Very often: Power electronic devices= Power semiconductor devices
Major material used in power semiconductor devices——Silicon
Major topics for each device
Appearance, structure, and symbol
Physics of operation
Specification
Special issues
Devices of the same family
Passive components in power electronic circuit
Transformer, inductor, capacitor and resistor: these are passive components in a power electron
ic circuit since they can not be controlled by control signal and their characteristics are usually constant and linear.
The requirements for these passive components by power electronic circuits could be very different from those by ordinary circuits.
Half- controlled device—Thyristor
Another name: SCR—silicon controlled rectifier
Thyristor Opened the power electronics era
–1956, invention, Bell Laboratories
–1957, development of the 1st product, GE
–1958, 1st commercialized product, GE
–Thyristor replaced vacuum devices in almost every power processing area.
Still in use in high power situation. Thyristor till has the
highest power-handling capability.
Other methods to trigger thyristor on
High voltage across anode and cathode—avalanche breakdown
High rising rate of anode voltagte —du/dt too high
High junction temperature
Light activation
Static characteristics of thyristor
Blocking when reverse biased, no matter if there is gate current applied.
Conducting only when forward biased and there is triggering current
applied to the gate.
Once triggered on, will be latched on conducting even when the gate current is no longer applied.
Typical fully- controlled devices
Features
–IC fabrication technology, fully- controllable, high frequency
Applications
–Begin to be used in large amount in 1980s
–GTR is obsolete and GTO is also seldom used today.
–IGBT and power MOSFET are the two major power
semiconductor devices nowadays.