1. POWER SEMICONDUCTOR DEVICES OVERVIEW

2. Historical 1st thyristor SCR developed in 1957
Since 1970, various type of power electronic devices were developed and become commercially available.

3. Power semiconductor Devices Classification
Classification by materials (carrier type)

4. The two-terminal devices (diodes), whose state is completely dependent on the external power circuit they are connected to;
The three-terminal devices, whose state is not only dependent on their external power circuit, but also on the signal on their driving terminal (gate or base). Transistors and thyristors belong to that category.
A second classification is less obvious, but has a strong influence on device performance: Some devices are majority carrier devices (Schottky diode, MOSFET), while the others are minority carrier devices (Thyristor, bipolar transistor, IGBT).
The former use only one type of charge carriers, while the latter use both (i.e electrons and holes). The majority carrier devices are faster, but the charge injection of minority carrier devices allows for better On-state performance

5. SCR / Thyristor module, 6500V, 1,500A for 50us pulse
Common power devices
Some common power devices are the power diode, thyristor, power MOSFET and IGBT. A power diode or MOSFET operates on similar principles to its low-power counterpart, but is able to carry a larger amount of current and typically is able to support a larger reverse-bias voltage in the off-state.
Structural changes are often made in power devices to accommodate the higher current density, higher power dissipation and higher reverse breakdown voltage. The vast majority of the discrete (non integrated) power devices are built using a vertical structure, whereas small-signal devices employ a lateral structure. With the vertical structure, the current rating of the device is proportional to its area, and the voltage blocking capability is achieved in the height of the die. With this structure, one of the connections of the device is located on the bottom of the semiconductor die
SCR / Thyristor module, 6500V, 1,500A for 50us pulse

6. Power semiconductor Devices Classification
Classification by control method

7. Power semiconductor Devices Classification
Classification by operation (direction of current flow)

8. The Ideal Switch - The Power Electronics Engineer's Dream
zero leakage current ð
support infinite voltage
zero forward voltage drop
zero conduction loss
instantaneous switching
zero switching loss
zero thermal resistance
infinite temperature capability
infinite current capability

9. The Ideal Switch - The Power Electronics Engineer's Dream (Cont..)
An impossible dream but advances in device and packaging technology have produced
conductivity modulated bipolar devices for high power applications at high temperatures
mosfet fabrication for high frequency switching

10. Generic Switch Symbol Idealized switch symbol
When on, current can flow only in the direction of the arrow
Instantaneous switching from one state to the other
Zero voltage drop in on-state
Infinite voltage and current handling capabilities

11. Characteristics of Practical Devices
Switching Power Loss is proportional to:
switching frequency
turn-on and turn-off times

12. POWER SEMICONDUCTOR DEVICES
Power Diode
Thyristors (11 types)
Transistors
Power Bipolar Junction Transistor (BJTs)
Power Metal Oxide Semiconductor field-effect transistors (MOSFETs)
Insulated-gate bipolar transistor (IGBTs)
Static Induction Transistors (SITs)

13. Power Diode On and off states controlled by the power circuit
An ideal diode should have the following characteristics:
When forward-biased, the voltage across the end terminals of the diode should be zero, whatever the current that flows through it (on-state);
When reverse-biased, the leakage current should be zero, whatever the voltage (off-state).
The transition between on and off states should be instantaneous

14. Types of diode Shottky diodes. Fast-recovery diodes.
Use where a low forward voltage drop is needed in very low output voltage circuit.
blocking voltage capability to V.
Fast-recovery diodes.
Used in high f circuit in combination with controllable switches, small recovery time.
At several hundred V and I, trr <μs
Line-frequency diodes.
On-state voltage is low as possible and as a sequence have larger trr which are acceptable for line-freq application.
Blocking voltage=several kV, I rating=several kA
Series and parallel for satisfy the requirement.

15. Power Diode Diode Turn-Off
Fast-recovery diodes have a small reverse-recovery time

16. Thyristors Semi-controlled device
Latches ON by a gate-current pulse if forward biased
Turns-off if current tries to reverse

17. Thyristor in a Simple Circuit
For successful turn-off, reverse voltage required for an interval greater than the turn-off interval

18. Bipolar Junction Transistors (BJT)
Used commonly in the past
Now used in specific applications
Replaced by MOSFETs and IGBTs

19. Various Configurations of BJTs

20. MOSFETs Easy to control by the gate
Optimal for low-voltage operation at high switching frequencies
On-state resistance a concern at higher voltage ratings

21. Gate-Turn-Off Thyristors (GTO)
Slow switching speeds
Used at very high power levels
Require elaborate gate control circuitry

22. GTO Turn-Off
Need a turn-off snubber

23. IGBT

24. MCT

25. Comparison of Controllable Switches

26. Summary of Device Capabilities