电力电子技术双语课件第4章
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Fourier series extension of output line-to-line voltage
u UV 2 3U d 1 1 1 1 sin 13t sin t sin 5t sin 7t sin 11t 5 7 11 13 2 3U d 1 k sin t ( 1 ) sin n t n n
10
Single-phase half bridge VSI
Ud 2
V1
VD io R
1
U G1 U G2 uo Um
Ud
Ud 2
L
uo
VD
V 2
2
Power
The current conducting path is determined by the polarity of load voltage and load current. (This is true for analysis of many power electronics circuits.)
Power
AC side current is quasisquare wave. AC side voltage is determined by the load. No anti-parallel diodes are needed. sometimes series diodes are needed to block reverse voltage for other power semiconductor devices.
R io
L
V4
uo
VD4
-
Power
Features DC side is constant voltage, low impedance (voltage source, or bulk cap) AC side voltage is square wave or quasi-square wave. AC side current is determined by the load. Anti-parallel diodes are necessary to provide energy feedback path. (freewheeling diodes , feedback diodes)
uo
S4
Power
A classification of inverters
– Square-wave inverters (are discussed in this chapter)
– PWM inverters ( will be discussed in Chapter 6)
The concept of commutation
(4-1)
Magnitude of output voltage fundamental component
Power
U o1m
4U d
1.27U d
(4-2)
Effective value of output voltage fundamental component
U o1 2 2U d
12
Single-phase full bridge VSI
Quantitative analysis
Fourier series extension of output voltage
uo 4U d 1 1 sin t sin 3 t sin 5 t 3 5
– Fuel cell
Power
As a part of composite converter
– AC-DC-AC frequency converter (for AC motor drive)
– AC-DC-AC constant-voltage constant-frequency converter (for uninterruptable power supplies)
io
t3
t4
t1 t2 t5 t6 V1 V2 V1 V2 VD1 VD2 VD1 VD2
The magnitude of output square-wave voltage is Ud/2.
11
Single-phase full bridge VSI
Operation principle
+
V3 VD1 C Ud V2 VD2 V1 VD3
U G1,4 U G2,3 uo Um
R io
L
VD V4
uo
4
io
Power
-
t3
t4
t1 t 2 t5 t6 V1 V2 V1 V2 V4 V3 V4 V3 VD 1 VD 2 VD 1 VD 2 VD 4 VD 3 VD 4 VD 3
The magnitude of output square-wave voltage is Ud. The effective value of output voltage (or fundamental output voltage) can be changed by changing Ud.
8
2 classes of inverters
Voltage Source Inverter (VSI) Current Source Inverter (CSI)
Power
9
4.2 Voltage source inverter (VSI)
+
C Ud V1 V2 VD2 VD1 V3 VD 3
Series connection of 2 single-phase VSIs
Power
24
Series connection of 2 3-phase VSIs
Power
25
Multi-level Inverters
Ways to deal with higher voltage and achieve better waveform
Device commutation For fully-controlled devices
Self-commutation
Forced commutation
Power
Line commutation
For thyristors
External commutation
Load commutation
Chapter 4 DC to AC Converters ( Inverters )
Applications of Inverters
Conversion of electric power from DC type energy sources to AC type load
– Battery – Photovoltaic cell (Solar cell)
6
Forced commutation (capacitance commutation)
Power
Direct-Coupled
With Coupling-Inductor
7
Another classification of commutations
4 types of Commutations
U UV1
U UV1m 2
6
U d 0.78U d
(4-11)
18
4.3 Current source inverter (CSI)
Features DC side is constant current, high impedance (current source, or large inductor)
0.9U d
(4-3)
13
Single-phase full bridge VSI
Output voltage control by phase-shift +
V3
uG1 O
VD 3
VD1
C U
d
V1 V2 VD2
uG2 O uG3 O uG4 O uo io O io t1 t2 t3 uo
4
4 types of commutation
Device commutation:
Fully-controlled devices: GTO, IGBT, MOSFET
Line commutation
Phase-controlled rectifier Phase-controlled AC controller Thyristor cycloconverter
20
Three-phase self-commutated CSI
Power
120o conduction
21
Three-phase force-commutated CSI
Power
22
Three-phase load-commutated CSI
Power
23
4.4 Multiple-inverter connections and multi-level inverters
(4-8)
Power
Magnitude of output voltage (line-to-line) fundamental component
U UV1m
2 3U d
1.1U d
(4-10)
Effective value of output voltage (line-to-line) fundamental component
19
Single-phase bridge CSI
Parallel Resonant Inverter
Ld A
Id
VT1 LT1 LT2 io uo R VT2
C
VT3 LT3 LT4
Power
L VT4
Switching frequency is a little higher than the resonant frequency so that the load becomes capacitive and load current is leading voltage to realize load commutation.
– AC-DC-AC Converters for induction heating – AC-DC-AC-DC switching power supplies
2
Outline
4.1 Commutation 4.2 Voltage source inverters
4.3 Current source inverters
t t t t
R io
L
VD 4 V4
Power
uo
-
t
14
Inverter with center-tapped transformer —push-pull inverter
Load
io
uo
Power
+来自百度文库
Ud V1 VD1 V2 VD2
-
15
Three-phase VSI
Power
180o conduction Dead time (blanking time) to avoid “shoot through”
16
Three-phase VSI
Basic equations to obtain voltage waveforms
For line voltage For phase voltage of the load
Power
UUN UVN UWN 0
17
Three-phase VSI
Quantitative analysis
– Series connection of multiple converters – Series connection of multiple switch devices
Major type of multi-level inverters
Power
4.4 Multiple-inverter connections and multi-level inverters
3
4.1 Commutation types
Basic operation principle of inverters
uo
S1 S3
Ud
S2
io
Load
io t1 t2 t
Power
Load commutation Forced commutation
5
Load commutation
Power
Condition: Load current is leading load voltage Application: capacitive load, synchronous motor
u UV 2 3U d 1 1 1 1 sin 13t sin t sin 5t sin 7t sin 11t 5 7 11 13 2 3U d 1 k sin t ( 1 ) sin n t n n
10
Single-phase half bridge VSI
Ud 2
V1
VD io R
1
U G1 U G2 uo Um
Ud
Ud 2
L
uo
VD
V 2
2
Power
The current conducting path is determined by the polarity of load voltage and load current. (This is true for analysis of many power electronics circuits.)
Power
AC side current is quasisquare wave. AC side voltage is determined by the load. No anti-parallel diodes are needed. sometimes series diodes are needed to block reverse voltage for other power semiconductor devices.
R io
L
V4
uo
VD4
-
Power
Features DC side is constant voltage, low impedance (voltage source, or bulk cap) AC side voltage is square wave or quasi-square wave. AC side current is determined by the load. Anti-parallel diodes are necessary to provide energy feedback path. (freewheeling diodes , feedback diodes)
uo
S4
Power
A classification of inverters
– Square-wave inverters (are discussed in this chapter)
– PWM inverters ( will be discussed in Chapter 6)
The concept of commutation
(4-1)
Magnitude of output voltage fundamental component
Power
U o1m
4U d
1.27U d
(4-2)
Effective value of output voltage fundamental component
U o1 2 2U d
12
Single-phase full bridge VSI
Quantitative analysis
Fourier series extension of output voltage
uo 4U d 1 1 sin t sin 3 t sin 5 t 3 5
– Fuel cell
Power
As a part of composite converter
– AC-DC-AC frequency converter (for AC motor drive)
– AC-DC-AC constant-voltage constant-frequency converter (for uninterruptable power supplies)
io
t3
t4
t1 t2 t5 t6 V1 V2 V1 V2 VD1 VD2 VD1 VD2
The magnitude of output square-wave voltage is Ud/2.
11
Single-phase full bridge VSI
Operation principle
+
V3 VD1 C Ud V2 VD2 V1 VD3
U G1,4 U G2,3 uo Um
R io
L
VD V4
uo
4
io
Power
-
t3
t4
t1 t 2 t5 t6 V1 V2 V1 V2 V4 V3 V4 V3 VD 1 VD 2 VD 1 VD 2 VD 4 VD 3 VD 4 VD 3
The magnitude of output square-wave voltage is Ud. The effective value of output voltage (or fundamental output voltage) can be changed by changing Ud.
8
2 classes of inverters
Voltage Source Inverter (VSI) Current Source Inverter (CSI)
Power
9
4.2 Voltage source inverter (VSI)
+
C Ud V1 V2 VD2 VD1 V3 VD 3
Series connection of 2 single-phase VSIs
Power
24
Series connection of 2 3-phase VSIs
Power
25
Multi-level Inverters
Ways to deal with higher voltage and achieve better waveform
Device commutation For fully-controlled devices
Self-commutation
Forced commutation
Power
Line commutation
For thyristors
External commutation
Load commutation
Chapter 4 DC to AC Converters ( Inverters )
Applications of Inverters
Conversion of electric power from DC type energy sources to AC type load
– Battery – Photovoltaic cell (Solar cell)
6
Forced commutation (capacitance commutation)
Power
Direct-Coupled
With Coupling-Inductor
7
Another classification of commutations
4 types of Commutations
U UV1
U UV1m 2
6
U d 0.78U d
(4-11)
18
4.3 Current source inverter (CSI)
Features DC side is constant current, high impedance (current source, or large inductor)
0.9U d
(4-3)
13
Single-phase full bridge VSI
Output voltage control by phase-shift +
V3
uG1 O
VD 3
VD1
C U
d
V1 V2 VD2
uG2 O uG3 O uG4 O uo io O io t1 t2 t3 uo
4
4 types of commutation
Device commutation:
Fully-controlled devices: GTO, IGBT, MOSFET
Line commutation
Phase-controlled rectifier Phase-controlled AC controller Thyristor cycloconverter
20
Three-phase self-commutated CSI
Power
120o conduction
21
Three-phase force-commutated CSI
Power
22
Three-phase load-commutated CSI
Power
23
4.4 Multiple-inverter connections and multi-level inverters
(4-8)
Power
Magnitude of output voltage (line-to-line) fundamental component
U UV1m
2 3U d
1.1U d
(4-10)
Effective value of output voltage (line-to-line) fundamental component
19
Single-phase bridge CSI
Parallel Resonant Inverter
Ld A
Id
VT1 LT1 LT2 io uo R VT2
C
VT3 LT3 LT4
Power
L VT4
Switching frequency is a little higher than the resonant frequency so that the load becomes capacitive and load current is leading voltage to realize load commutation.
– AC-DC-AC Converters for induction heating – AC-DC-AC-DC switching power supplies
2
Outline
4.1 Commutation 4.2 Voltage source inverters
4.3 Current source inverters
t t t t
R io
L
VD 4 V4
Power
uo
-
t
14
Inverter with center-tapped transformer —push-pull inverter
Load
io
uo
Power
+来自百度文库
Ud V1 VD1 V2 VD2
-
15
Three-phase VSI
Power
180o conduction Dead time (blanking time) to avoid “shoot through”
16
Three-phase VSI
Basic equations to obtain voltage waveforms
For line voltage For phase voltage of the load
Power
UUN UVN UWN 0
17
Three-phase VSI
Quantitative analysis
– Series connection of multiple converters – Series connection of multiple switch devices
Major type of multi-level inverters
Power
4.4 Multiple-inverter connections and multi-level inverters
3
4.1 Commutation types
Basic operation principle of inverters
uo
S1 S3
Ud
S2
io
Load
io t1 t2 t
Power
Load commutation Forced commutation
5
Load commutation
Power
Condition: Load current is leading load voltage Application: capacitive load, synchronous motor