電力電子元件簡介
Introduction to Power Electronic Devices
C. M. Liaw
Department of Electrical Engineering
National Tsing Hua University
Hsinchu, Taiwan, ROC.
無段式電熱控制
(應用 SCR)
兩段式電熱控制
(應用 Power diode)
AC
source
SCR
Power diode
AC
source
P
Load
Load
Firing circuit
Diode: Uncontrolled turn-on and
turn-off
SCR: Controlled turn-on and
uncontrolled turn-off
可控制交流輸出電壓
故控制性能較佳
不可控制交流輸出電壓
故控制性能較差
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常用功率半導體元件之額定(表二)
Voltage/current ratings
Switching frequency (speed)
Switching time
On-state resistance
(or on-state voltage/current)
功率半導體元件
功率半導體元件
(A) 閘流體 (Thyristor) 或矽控整流器 (Silicon Controlled
Rectifier, SCR) : Controlled turn-on, uncontrolled turn-off
(B) 雙向閘流體 (Bidirectional Thyristor 或 TRIAC)
(C) GTO (Gate Turn-off Thysistor)
(D) 基體閘換向閘流體 (Integrated Gate-Commutated Thyristor, IGCT):
It is introduced by ABB in 1997. It is a high-voltage, hard-driven,
asymmetrical-blocking GTO with unity gain. The gate drive circuit
is built-in on the device module.
(E) 功率電晶體 (Power BJT) : Current control device
(F) IGBT (Insulated Gate Bipolar Transistor):
- Combines the conduction characteristic of BJT and
the control characteristic of the MOSFET
(G) MOS控制閘流體 (MOS -controlled Thyristor, MCT):
- Combines the load characteristic of the thyristor and
the control characteristic of the MOSFET
- Low on-state voltage
(H) 功率金氧半電晶體 (Power MOSFET) : Voltage control device
(I) 其它
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耐壓
耐流
操作
速度
功率半導體元件之控制特性
功率半導體元件之控制特性
(1) Uncontrolled turn-on and off: (diode)
(2) Controlled turn-on and uncontrolled turn-off: (SCR)
(3) Controlled turn-on and off (Controllable switches):
(GTO, IGCT, MCT, BJT, IGBT, MOSFET)
(4) Continuous gate signal requirement: (IGCT, BJT, IGBT,
MOSFET)
(5) Pulse gate signal requirement: (MCT, SCR, TRIAC, GTO)
(6) Bipolar voltage-withstanding capability: (SCR)
(7) Unipolar voltage-withstanding capability: (GTO, IGCT,
MCT, BJT, IGBT, MOSFET)
(8) Bidirectional current capability: (TRIAC)
(9) Unidirectional current capability: (SCR, GTO, IGCT, MCT,
BJT, IGBT, MOSFET, diode)
Power Semiconductors
Classification of
state-of-the-art
Power Semiconductors
SiC
Page 3
常用功率半導體元件之符號
及操作特性
功率換流器之典型結構
功率換流器之典型結構
(強電)
Power
source
(AC, DC)
Input
filter
(濾波及/或
功因控制)
Command
型
型 式:
式:
Power
Converter
Output
filter
(隔離、驅動)
Switching
Control Signal
Generator
Feedback
Output source
(to load)
Loads:
Power supplies
Motor drives
(弱電)
• 交流至交流交流至交流換流器 (Cycloconverter)
(含交流至直流至交流換流器)
• 交流至直流換流器 (Converter): Phase control, integral cycle control
• 直流至交流換流器 (Inverter): VVVF, VVFF
• 直流至直流換流器 (Chopper): PWM control, FM control
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如何設計一個電力電子設備
如何設計一個電力電子設備 ??
(1) 由機械負載特性選定馬達及換流器之型式。
(2) 設計組裝電力電路：選定功率半導體元件、組裝換流器
及其保護電路。
(3) 決定並設計適當之換流器切換控制方式及電路。
(4) 設計邏輯決策電路、隔離電路及觸發驅動電路。
(5) 設計輸入及輸出濾波電路(功因控制電路)。
(6) 感測元件及其信號放大處理電路之組立。
(7) 電力電子系統之動態模式建立：推導或由量測估算得之。
(8) 閉迴路控制系統之設計及實作。
(9) 組裝(注意接地與屏蔽等考量安排設計)。
常用功率半導體簡介
Power diodes:
General purpose (for high-power rectification)
High speed (for switching application)
Schottky (for extra-low voltage rectification)
Thyristors
Power transistors
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SCR (矽控整流器)
閘流體 (Thyristor)- 矽控整流器 (Silicon Controlled Rectifier,
SCR) : Controlled turn-on, uncontrolled turn-off
Construction, symbol, equivalent circuit, triggering control,
v-i characteristics:
A
A
A
P
P
N
N N
G
P
G
A
N
K
G
P P
i c1 = ib2
G
N
K
Q1
K
i c2 = ib1
Q2
K
Two-transistor model
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SCR之逆偏
v AK > V RB (V RWM ) Þ Breakdown
i AK
i AK » 0
A
P
-
RB
N
FB
G
P
+
RB
N
VRB (VRWM )
IH
iG1 > iG2 > iG3
vAK
VFB (VBO )
K
SCR之順偏
順偏:
i AK
i AK
A
P
N
G
P
iGK
N
FB
RB
FB
+
-
VRB (VRWM )
K
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IH
iG1 > iG2 > iG3
VFB (VBO )
vAK
Two-transistor model
ib Þ i c Þ ib Þ i c Þ (Current is cumulatively amplified)
Normally triggered: 當 v AK > 0 時，加以適當之 i GS > 0
Abnormally triggered:
High dv/dt
High temperature
v AK > V FB
A
Q1
i c1 = i b 2
i c2 = i b1
Q2
G
K
觸發控制
Turn on:
Turn off:
當 v AK > 0 時，加以適當之 i GS > 0
i AK < I H ( Holding current )
在使用時，須注意外加之電壓
正負峰值不可大於順向崩潰
電壓 V FB 及逆向崩潰電壓 V RB 。
VRB (VRWM )
i AK
IH
iG1 > iG2 > iG3
VFB (VBO )
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vAK
沒有 Gate 之SCR
Þ
蕭克萊二極體 (Shockley diode)
on 及 off:
v AK ³ V
FB
符號：
Þ ON ,
A
i AK < I H Þ OFF
K
Triac (AC Thyristor)
A three-terminal, five layer, bilateral semiconductor device.
Bidirectional TRIode AC thyristor.
TRIAC
T1
Tab electrically
connected to T2
T2
G
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Triac 之簡易測試
TRIAC
Power supply
IT48TH
-
+
-
+
T1 T2 G
TRIAC
T2
A three-terminal,
five layer, bilateral
semiconductor device.
N3
P2
T 2 ® T1 : P2 - N2 - P1 - N1
T 1 ® T 2 : P1 - N2 - P2 - N3
N2
N1
T1
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P1
N4
G
TRIAC: 為兩個反並接之SCR，可於正負半週觸發導通，
為具 bidirectional current capability 之元件。
G
符號：
T1 ( A )
T2 ( K )
Þ
T2
T1
G
當 v AK > 0 時，加以適當之 i GK > 0
觸發控制
Turn on:
當 v AK < 0 時，加以適當之 i GK < 0
i AK < I H ( Holding current )
Turn off:
i AK
+
vT =
vT 2-T1
-
T2
T1
iT =
iT 2 - T 1
VRB
G
IH
iG 1 > iG 2 > iG 3
VFB
iG
vT
(v AK )
Typical Applications of SCR and TRIAC
n Converter power control
(1) Phase control
(2) Integral cycle control
n SSR (Solid State Relay) or AC Switch
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2 -T1
可控開關 (Controllable Switches)
iT
元件：(1) Forced-commutated SCR
Control
signal
(2) BJT, MOSFET, IGBT, MCT, ...
Switching speed -Switching losses ¯¯
暫態:
穩態:
(1) Off : Leakage current ¯¯
R
ON
¯¯ ,
V
ON
iT
vT
V ON
¯¯
p T = v T ´ iT
R ON
V ON
Conduction loss ¯¯
iT
turn-off
turn-on
(Switching losses)
Power BJT
Current-controlled device
IB
-
pT =vT ´ iT
所欲之特性：
(2) On :
+
vT
C
IC
B
E
Turn on:
I B ³ I C ,sat / b min
Page 12
t
Power BJT
Voltage ratings: (primary breakdown)
BV SUS ,
BV CEO ,
BV CBO
VCB , max (E is open circuited)
VCE , max (B is open circuited)
VCE ,max when I C ¹ 0
Secondary breakdown:
Caused by large di/dt at turn-on instant.
Power BJT
b is smaller compared with small-signal BJTs.
Hard saturation and quasi-saturation:
Quasi-saturation:
I B = I C ,sat / b min
iC
IB
Hard-saturation:
Conduction loss
Switching speed
I B > I C , sat / b min
v CE
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Power MOSFET
Voltage-controlled device
Turn on: v GS > v GS , th
i G ,steady - state » 0 (very small)
D
v GS
v GS
G
v GS , th
Parasitic C
v GS
,max
S
Power MOSFET
> v GS > v GS ,th
v GS - Þ i D ,sat - , Ron ¯ , Pswitching 2 .5 ~ 2 . 7
R DS ,on = k BV DS
n Light load:
Switching loss dominant :
v GS ¯ Þ P g = Q g vGS f sw ¯
Q g = total gate charge
n Heavy load:
Conduction loss dominant :
v GS - Þ R DS ,on ¯
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iD
1 / Ron
vGS2 > vGS1
vGS1
iD2 > iD1
iD1
v DS
Cool MOSFET
It is a new revolutionary technology for high voltage
power MOSFETs. It implements a compensation
structure in the vertical drift region of a MOSFET in
order to improve the on-state resistance.
R DS ,on ¯ , Q g ¯ , q JA slightly higher (~ 10%)
Pulse current rating is lower.
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Page 16
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Page 18
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Power MOSFET 與 Power BJT 之比較
Power MOSFET
(Enhancement mode)
D
觸發控制
Turn on:
G
+
v GS
- S
導通
特 性:
Power BJT
觸發控制
Turn on:
C
B
IB
IC
E
導通
特 性:
{
{
{
{
R ON
V ON
v GS > v GS ,th , i G , steady - state » 0( very small )
為電壓控制元件
需有特殊驅動電路以加速 switching speed
VON = 0, RON 較大，但綜合導通損較大。
電阻之溫度係數為正，無 Thermal run away
問題，並聯分流特性佳。
I B > I C,sat / bmin , 為電流控制元件
需有電流放大之驅動電路，
switching speed 比MOSFET慢
V ON = V CE , sat , R ON
較小，但綜合導通損
較MOSFET小。
電阻之溫度係數為負，有 Thermal run away
問題，不易並聯分流。
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IGBT (Insulated-Gate Bipolar Transistor)
MOSTFET + BJT
IGBT (Insulated Gate Bipolar Transistor):
- Combines the conduction characteristic of BJT
and the control characteristic of the MOSFET
Symbol and equivalent circuit:
C(D)
G
C(D)
E(S)
G
C(D)
C(D)
G
G
E(S)
E(S)
E(S)
v GS
C(D)
G
E(S)
Printed circuit
board
絞線以防電磁耦合
干擾，線短且勿太細
Damping
filter
Page 21
MCT (MOS-controlled Thyristor)
MOSTFET + Thyristor
Combines the load characteristic of thyristor
and the control characteristic of MOSFET
Low on-state voltage
Symbol
A(Anode)
G
K (Cathode)
Turn on: 加負脈衝 VGA
使 p-ch MOSFET M1
導通，提供BJT Q2 之
基極電流，使MCT on。
A
D2
M2
G
Turn off: 加正脈衝 VGA
使 n-ch MOSFET M2
導通，將BJT Q1 之
Thyristor
基極與射極短接，
使MCT off.
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S1
G
S2
Q1
D1
M1
Q2
K
+
-
Triggering Devices (觸發元件)
產生觸發控制脈波，以觸發功率半導體開關
n 蕭克萊二極體 (Shockley diode), Four-layer diode
n DIAC
n UJT (Uni-junction Transistor)
n PUT (Programmable Uni-junction Transistor)
n SUS (Silicon Unilateral Switch)
n SBS (Silicon Unilateral Switch)
n 其他
蕭克萊二極體 (Shockley diode)
沒有 Gate 之SCR
Þ
on 及 off:
v AK ³ V
FB
符號：
Þ ON ,
A
Page 23
i AK < I H Þ OFF
K
DIAC (沒有 Gate 之 TRIAC)
on 及 off:
v AK > 0: v AK ³ V FB Þ ON , i AK < I H Þ OFF
v AK < 0:
v AK ³ V RB Þ ON ,
i AK < I H Þ OFF
i AK
符號：
T1
IH
VRB
T2
v AK
IH
VFB
單接面電晶體(Uni-Junction Transistor, UJT)
UJT
B2
B2
E
VD
E
p
n
+
rB 2
rB1
IE
V EB
-
B1
TO-18 package
B1
B2
B1
E
Page 24
B2 electrically
connected to case
Emitter Characteristic Curve
I E ( mA )
B2
E
+
VEB
I E « VEB
+
VBB
-
IE
IV
B1
-
Peak voltage
D
h=
V
VV
V p = VD +
P
VEB (V )
VP
D
rB1
VB2, B1 = VD + hVB2, B1
rB1 + rB2
rB1
: ( Intrinsic standoff ratio ,本質分立比)
rB1 + rB 2
Application: Relaxation OSC. (鬆弛振盪器)
V C1
VP
VV
R2
R1
+
E
VBB
-
C1
+
V C1
-
t
V o1
T2
B2
B1
+
G
Vo1
T » R1 C1
T1
t
R3 Vo2
-
Vo 2
T » R1 C1
t
Positive going pulse
Page 25
Programmable Unijunction Transistor, PJT)
PJT
A
G
A
A
G
G
P
Q1
N
n
P
Q2
N
K
K
K
V p = VD +
D
R3
VBB = VD + hVBB
R2 + R3
h 可由外加之電阻定之
V p = VD +
D
R3
VBB = VD + hVBB
R2 + R3
R1
+
Vo1
VBB
-
R2
A
Vo3
G
K
C1
R4
Page 26
R3
T2
Vo2 G
T1
SiC (Silicon Carbide) Power Devices
Page 27
Introduction to SiC
Silicon Carbide (SiC) is a wide-bandgap semiconductor, which has been intensively studied in the
recent years, due to its physical properties , such as high breakdown field, high saturated drift
velocity and high thermal conductivity. This characteristics make SiC a very good candidate for
the applications in which high temperature, high radiation intensity, high voltage or high power
dissipation are involved, such as temperature sensors, nuclear radiation detectors, UV detectors,
microwave devices and power devices.
Although of the high potential of this material for the use in the electronic industry, the SiC
technology shows some limitations and requires further study in order to obtain electronic devices of
the same quality standards as Si technology:
• the bulk growth of SiC is still very expensive and material quality is still lower than device
production requirements;
• the epitaxial growth is necessary to obtain device-quality material, but it requires high
temperature processes;
• selective doping of SiC layers requires the use of ion implantation, since the diffusion coefficients
for the doping species are too small for practical applications;
• the realization of ohmic contacts on SiC is difficult and requires high temperature processes;
• the thermal oxidation of SiC is difficult due to the high temperature needed and the quality of the
material obtained is still lower respect to Si oxidation.
These limitations underline the need of further study in the SiC field. In particular, the growth of
epitaxial layers is a first-step process for the realization of a wide variety of electronic devices.
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