电力电子技术基础(英文) 蒋晓华Cha1Devices
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to minimize the anode-cathode voltage
Turn-off conditions:
by applying a negative voltage across the gate-cathode
a. turn-off voltage high enough but less than the breakdown b. a reverse gate current with a peak value of
by a relatively small controlling current or voltage
Study focuses: (Diode, SCR, GTO, BJT, MOSFET, IGBT, IPM) characteristics, rather than the physics firing requirements ratings comparisons of the devices
Power Devices
Turn-on conditions:
similar to the thyristor but the latching current higher & the gate current continuous
a. turn-on high level gate current for a longer time b. after turn-on a low level of gate current
1/5~1/3 of the anode current established in less than 1μs
Power Devices
1-4. Power Transistor (GTR / BJT)
Chapter 1 Power Devices
a power device ~ a switch
Switching States:
* on state (static)
ຫໍສະໝຸດ Baidu
Von-state = 0 ideally
Current ratings – continuous, average, RMS, peak
Power Devices
Firing requirements
a. Gate-cathode — poor P-N junction
within a given production batch
Igmin < Ig < Igmax Vgmin < Vg < Vgmax IgVg < Pgmax
b. pulse firing current
with a fast rise and a sufficient length
1-3. GTO (Gate Turn-off Thyristor)
Power Devices
A reverse voltage with the cathode positive will break down the anode junction at a low level.
Power Devices
Wstatic =Won+ Woff = on-time ion(t)von-state(t)dt + off-time ileakage(t)voff(t)dt
pswitch Wswitch = turn-on i(t)v(t)dt + turn-off i(t)v(t)dt Paverage = (Wstatic+Wswitch)/T
1-2. Thyristor (SCR)
Ib1
+ Anode
Ia
P
Power Devices
Structure and symbol
N
Ib2 AnGodatee
P Ig N
Ic
- Cathode
IgIb1
Ia, Ic
Cathode
Ib2
ChaCrhaactreaPrcoitssetiritciisvtewicfisetehwdinbtohacgkate current
* off state (static)
Ileakage = 0 ideally
off-state voltage ratings - forward and reverse
* commutation state (dynamic)
dv/dt rating
dv/dt, di/dt = ideally
Won--- major loss at lower-frequency operation Wswitch--- significant at high-frequency operation
Power Devices
A POWER SWITCHING DEVICE
* permits current flow in one direction only * can withstand a forward voltage (except diodes) * can be turned on or off
(an equivalent capacitor in off-state, a displacement current i = C dv/dt)
di/dt rating
(a hot point in the region where the first conduction occurs)
Switch Energy Losses:
(a) Conventional thyristor symbol. (b) Conventional thyristor P-N-P-N structure. (c) Gate turn-off thyristor symbol. (d) Gate turn-off thyristor structure.
1-1. Diode
Power Devices
Structure and symbol
Characteristics
Power Devices
reverse recovery time trr
Typical turn-off condition of a diode. Fast Recovery Diode trr
Turn-off conditions:
by applying a negative voltage across the gate-cathode
a. turn-off voltage high enough but less than the breakdown b. a reverse gate current with a peak value of
by a relatively small controlling current or voltage
Study focuses: (Diode, SCR, GTO, BJT, MOSFET, IGBT, IPM) characteristics, rather than the physics firing requirements ratings comparisons of the devices
Power Devices
Turn-on conditions:
similar to the thyristor but the latching current higher & the gate current continuous
a. turn-on high level gate current for a longer time b. after turn-on a low level of gate current
1/5~1/3 of the anode current established in less than 1μs
Power Devices
1-4. Power Transistor (GTR / BJT)
Chapter 1 Power Devices
a power device ~ a switch
Switching States:
* on state (static)
ຫໍສະໝຸດ Baidu
Von-state = 0 ideally
Current ratings – continuous, average, RMS, peak
Power Devices
Firing requirements
a. Gate-cathode — poor P-N junction
within a given production batch
Igmin < Ig < Igmax Vgmin < Vg < Vgmax IgVg < Pgmax
b. pulse firing current
with a fast rise and a sufficient length
1-3. GTO (Gate Turn-off Thyristor)
Power Devices
A reverse voltage with the cathode positive will break down the anode junction at a low level.
Power Devices
Wstatic =Won+ Woff = on-time ion(t)von-state(t)dt + off-time ileakage(t)voff(t)dt
pswitch Wswitch = turn-on i(t)v(t)dt + turn-off i(t)v(t)dt Paverage = (Wstatic+Wswitch)/T
1-2. Thyristor (SCR)
Ib1
+ Anode
Ia
P
Power Devices
Structure and symbol
N
Ib2 AnGodatee
P Ig N
Ic
- Cathode
IgIb1
Ia, Ic
Cathode
Ib2
ChaCrhaactreaPrcoitssetiritciisvtewicfisetehwdinbtohacgkate current
* off state (static)
Ileakage = 0 ideally
off-state voltage ratings - forward and reverse
* commutation state (dynamic)
dv/dt rating
dv/dt, di/dt = ideally
Won--- major loss at lower-frequency operation Wswitch--- significant at high-frequency operation
Power Devices
A POWER SWITCHING DEVICE
* permits current flow in one direction only * can withstand a forward voltage (except diodes) * can be turned on or off
(an equivalent capacitor in off-state, a displacement current i = C dv/dt)
di/dt rating
(a hot point in the region where the first conduction occurs)
Switch Energy Losses:
(a) Conventional thyristor symbol. (b) Conventional thyristor P-N-P-N structure. (c) Gate turn-off thyristor symbol. (d) Gate turn-off thyristor structure.
1-1. Diode
Power Devices
Structure and symbol
Characteristics
Power Devices
reverse recovery time trr
Typical turn-off condition of a diode. Fast Recovery Diode trr