1/21/2013
Ho Chi Minh City University of Technology
PGS.TS Lê Minh Phương
Khoa Điện –Điện Tử
Trường Đại Học Bách Khoa TP HỒ CHÍ MINH
Contact info: Address: 268 Lý Thường Kiệt, P.14,Q.10, TP Hồ Chí Minh Telephone: 84-08-38647256 (5722) Mobile: 0988572177 E-mail: lmphuong@hcmut.edu.vn; ivanphuong@yahoo.com 1
Power Electronics
Chương 2
BỘ NGHỊCH LƯU – BIẾN TẦN
2
POWER INVERTER PGS.TS Lê Minh Phương Khoa Điện –Điện Tử Trường ĐHBK TPHCM TPHCM 2012
1
1/21/2013
Contents – Nội dung
1. Tổng quan 2. Bộ nghịch lưu áp a. Cấu hình b. Nguyên lý làm việc c. Phương pháp điều khiển d. Mô hình hóa bằng Matlab-Simulink
3. Bộ nghịch lưu dòng
a. Cấu hình b. Nguyên lý làm việc c. Phương pháp điều khiển d. Mô hình hóa bằng Matlab-Simulink
3
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Bộ nghịch lưu áp - VSI
Bộ nghịch lưu áp – Voltage Source Inverter (VSI)
2. Bộ nghịch lưu áp 3 pha
1. Nguyên lý làm việc
2. Phương pháp điều khiển
3. Mô phỏng Matlab-Simulink
4
2
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Bộ nghịch lưu áp - VSI
Bộ nghịch lưu áp 3 pha
Q1~Q6 ─IGBTs, switching devices
5
D1~D6 ─Freewheeling diodes on C ─dc filter capacitor (VSI) Vs ─dc link voltage The switches of any leg of the inverter (S1 and S4, S3 and S6, or S5 and S2) cannot be simultaneously switched because this would result in a short circuit across the dc link voltage supply 1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Bộ nghịch lưu áp 3 pha
6
3
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Bộ nghịch lưu áp - VSI
Bộ nghịch lưu áp 3 pha
7
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Bộ nghịch lưu áp 1 pha
Square wave operation
Note: Period I: Q5, Q6 and Q1 on Period II: Q6, Q1 and Q2 on Period III: Q1, Q2 and Q3 on Period IV: Q2, Q3 and Q4 on Period V: Q3, Q4 and Q5 on Period VI: Q4, Q5 and Q6 on
8
4
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1/21/2013
Bộ nghịch lưu áp 1 pha
VaN=1/3(2Va0-Vb0-Vc0) Vab=Vs(g1-g3)
VbN=1/3(2Vb0-Va0-Vc0) Vbc=Vs(g3-g5)
VcN=1/3(2Vc0-Va0-Vb0) Vca=Vs(g5-g1)
9
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Bộ nghịch lưu áp 3 pha
Waveforms, phase voltage on load
Note: vg1 and vg4 are complimentary
vg3 and vg6 are complimentary
vg5 and vg2 are complimentary
Va0 is controlled by g1, g4.
Vb0 is controlled by g3, g6.
10
Vc0 is controlled by g5, g2.
5
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Bộ nghịch lưu áp 3 pha
Waveforms, phase voltage on load
VaN=1/3(2Va0-Vb0-Vc0)
VbN=1/3(2Vb0-Va0-Vc0)
VcN=1/3(2Vc0-Va0-Vb0)
11
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp 3 pha
Waveforms, line voltage on load
12
Vab=Vs(g1-g3) Vbc=Vs(g3-g5) Vca=Vs(g5-g1)
6
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Bộ nghịch lưu áp 1 pha
Analysis
Trị hiệu dụng điện áp dây có thể tính
Điện áp tải tức thời theo phân tích Fourier
13
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Bộ nghịch lưu áp 1 pha
Trị hiệu dụng hài cơ bản điện áp tải:
Dòng điện tải tức thời theo phân tích Fourier
Trong đó: n - góc lệch pha trong hài bậc n dòng điện tải
14
7
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1/21/2013
Bộ nghịch lưu áp 3 pha
Load neutral voltage
Note: In practical design, the neutral of capacitors is not grounded because of the grounded three phase power supply.
15
Neutral point grounded three-phase inverter
vn: voltage of load neutral respect to ground vA0: voltage of node A respect to ground vB0: voltage of node B respect to ground vC0: voltage of node C respect to ground PGS.TS Le Minh Phuong 1/21/2013
Bộ nghịch lưu áp 3 pha
Load neutral voltage
16
8
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Bộ nghịch lưu áp 3 pha
Nhận xét
Thay đổi tần số điện áp tải bằng cách thay đổi
tần số f (chu kỳ T)
Muốn thay đổi trị hiệu dụng điện áp tải phải điều
chỉnh được điện áp Vs
Dòng điện tải không hoàn toàn Sin. Cần phải
lọc thành phần DC bằng tụ.
Thành phần hài bậc bộ số của 3 bằng 0 (triple -
order harmonics are not presented)
17
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Bộ nghịch lưu áp – Voltage Source Inverter (VSI)
2. Bộ nghịch lưu áp 3 pha
1. Nguyên lý làm việc
2. Phương pháp điều khiển
3. Mô phỏng Matlab-Simulink
19
9
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
Note:
(1) Modulating waves: three-phase
sinewaves (vmA, vmB, vmC) with
adjustable amplitude and frequency
(2) Carrier wave: triangular wave,
fixed amplitude, frequency may be
adjusted, depends on applications
(3) vmA≥vc →Q1 on
vmA
20
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
Also, the inverter output voltage has
the following features:
ƒ PWM frequency is the same as the
frequency of Vtri
ƒ Amplitude is controlled by the peak
value of Vcontrol
ƒ Fundamental frequency is
controlled by the frequency of
Vcontrol
21
10
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Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
(3) vmA≥vc →Q1 on→vA0=Vs/2
vmA
22
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
23
The three-phase VSI. Ideal
waveforms for the SPWM
(ma = 0.8, mf = 9):
(a) carrier and modulating signals
(b) switch S1 state;
(c) switch S3 state;
(d) ac output voltage;
11
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1/21/2013
Bộ nghịch lưu áp - VSI
Phân tích phổ điện áp dây tải
The three-phase VSI. Ideal waveforms for
the SPWM (ma = 0.8, mf = 9):
(d) ac output voltage;
(e) ac output voltage spectrum;
24
The harmonics in the ac output
voltage appear at normalized
frequencies fh centered around
mf and its multiples, specifically,
at h = l mf ±k l= 1, 2, . . .
where l = 1, 3, 5, . . . for k = 2, 4,
6, . . . and l = 2, 4, . . . For k = 1,5,
7, . . . Such that h is not a
multiple of 3. Therefore, the
harmonics will be at mf ± 2, mf ±
4, . . ., 2mf ± 1, 2mf ± 5, . . ., 3mf
± 2, 3mf ± 4, . . ., 4mf ± 1, 4mf ±
5, . . ..
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp tải
25
12
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Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp
26
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phân tích phổ dòng điện DC-link
The three-phase VSI. Ideal waveforms for
the SPWM (ma = 0.8, mf = 9:
(g) dc current; (h) dc current spectrum;
27
For nearly sinusoidal ac load
current, the harmonics in the dc
link current are at frequencies
given by h = l mf ± k ± 1 l = 1, 2,
. . . where l = 0, 2, 4, . . . for k =
1, 5, 7, . . . and l = 1, 3, 5, . . . for
k = 2, 4, 6, . . . such that h = l ·
mf ± k is positive and not a
multiple of 3. For instance, Fig
shows the sixth harmonic (h =
6), which is due to h = 1 · 9 − 2
− 1 = 6.
13
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
28
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf=9):
(i) switch S1current; and
(j) diode D1 current.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
In the linear region (ma ≤ 1) the maximum amplitude of the
fundamental ac output line voltage is √3vi /2. Therefore, one can write
29
To further increase the amplitude of the load voltage, the amplitude of
the modulating signal ˆvc can be made higher than the amplitude of the
carrier signal ˆv, which leads to overmodulation. The relationship
between the amplitude of the fundamental ac output line voltage and
the dc link voltage becomes non-linear
14
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Square-wave Operation of Three-phase VSIs
as
Large values of ma in the
SPWM technique lead to full
is
overmodulation.
This
known
square-wave
The ac line output voltage
operation as illustrated in Fig,
contains the harmonics fh,
where the power valves are
Where h = 6 · k ± 1 (k = 1, 2,
on for 180◦.
3, . . .) and they feature
amplitudes
that are inversely proportional
to their harmonic order
30
(c)ac output voltage; and
(d) ac output voltage spectrum.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
This approach expands the range of the linear region as it allows
the use of modulation indexes ma up to 2/√3 without getting into the
overmodulating region
to
A zero sequence signal is
the modulating
added
they are
signals before
compared
the carrier
signal
31
to
15
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
the
Zero sequence signal generator (ma = 1.0, mf = 9):
(b) modulating signals; and
(c) zero sequence and modulating signals with zero sequence injection.
32
The addition of the zero
the
sequence
reduces
peak amplitude of
the
modulating
resulting
signals (uca , ucb , ucc ),
fundamental
while
components
remain
unchanged
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
The maximum amplitude of the fundamental phase voltage in the linear
region ma ≤ 2/√3 is vi /2, thus, the maximum amplitude of the
fundamental ac output line voltage is vi
33
16
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Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
VSI. three-phase
The
Ideal
waveforms for the SPWM (ma = 0.8,
mf = 9) with zero sequence signal
injection:
(a) modulating signals;
(b) carrier and modulating signals
with zero sequence signal injection;
34
(c) switch S1 state;
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
35
The
three-phase VSI.
Ideal waveforms for the
SPWM (ma = 0.8, mf = 9)
with zero sequence signal
injection:
(d) ac output voltage;
(e) ac output voltage
spectrum;
17
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
As in single-phase VSIs, the SHE technique can be applied to three-
phase VSIs
36
The harmonics multiples of 3 (h = 3, 9, 15, . . .), could be present in the
phase voltages (vaN , vbN , and vcN ), and will not be present in the
load voltages (vab, vbc , and vca )
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
Thus the chopping angles are used to eliminate only the harmonics
at frequencies h = 5, 7, 11, 13, . . . as required.
37
To eliminate the fifth and seventh harmonics and perform fundamental
magnitude control (N = 3),
18
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
38
Chopping angles for SHE and fundamental voltage
control in three-phase VSIs: fifth and seventh harmonic elimination.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
39
The three-phase VSI. Ideal waveforms for the SHE technique: (a)
phase voltage vaN for fifth and seventh harmonic elimination;
(b) spectrum of (a); (c) line voltage vab for fifth and seventh harmonic
elimination; and (d) spectrum of (c).
19
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Bộ nghịch lưu áp - VSI
Điều chế giảm hài bậc 3 trong điện áp pha
40
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Bộ nghịch lưu áp - VSI
Delta Modulation
41
Ia* - Reference current (phase A) ia*
Ia - actual inverter output current (phase A)
ia - error signal (phase A)
20
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Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện
Delta Modulation
As a result, the actual current ia will be
kept within the upper and lower band limits
Note:
(1) Assume vg1=“1”→G1
If reference current
is
on→ia↑ until t1
sine wave, actual current is
(2) At t1, ia reaches the
also sine wave on which
UBL→vg1=“0”→vg4=“1”→
order
high
some
G4on→ia↓ until t2
are
harmonics
(3) At t2, ia reaches the LBL
→vg1=“1”→vg4=“0”→G1
superimposed. High order
on→ia↑
harmonics can be filtered
out easily.
No low order harmonics.
Inverter output current
can
accurately
controlled
42
be
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện
Delta Modulation
43
21
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Power Electronics
For Building
THANK YOU
FOR YOUR ATTENTION
44
22
1/21/2013
20
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
Also, the inverter output voltage has the following features: ƒ PWM frequency is the same as the frequency of Vtri ƒ Amplitude is controlled by the peak value of Vcontrol ƒ Fundamental frequency is controlled by the frequency of Vcontrol
21
10
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
(3) vmA≥vc →Q1 on→vA0=Vs/2
vmA
22
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
23
The three-phase VSI. Ideal
waveforms for the SPWM
(ma = 0.8, mf = 9):
(a) carrier and modulating signals
(b) switch S1 state;
(c) switch S3 state;
(d) ac output voltage;
11
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Phân tích phổ điện áp dây tải
The three-phase VSI. Ideal waveforms for
the SPWM (ma = 0.8, mf = 9):
(d) ac output voltage;
(e) ac output voltage spectrum;
24
The harmonics in the ac output
voltage appear at normalized
frequencies fh centered around
mf and its multiples, specifically,
at h = l mf ±k l= 1, 2, . . .
where l = 1, 3, 5, . . . for k = 2, 4,
6, . . . and l = 2, 4, . . . For k = 1,5,
7, . . . Such that h is not a
multiple of 3. Therefore, the
harmonics will be at mf ± 2, mf ±
4, . . ., 2mf ± 1, 2mf ± 5, . . ., 3mf
± 2, 3mf ± 4, . . ., 4mf ± 1, 4mf ±
5, . . ..
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp tải
25
12
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp
26
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phân tích phổ dòng điện DC-link
The three-phase VSI. Ideal waveforms for
the SPWM (ma = 0.8, mf = 9:
(g) dc current; (h) dc current spectrum;
27
For nearly sinusoidal ac load
current, the harmonics in the dc
link current are at frequencies
given by h = l mf ± k ± 1 l = 1, 2,
. . . where l = 0, 2, 4, . . . for k =
1, 5, 7, . . . and l = 1, 3, 5, . . . for
k = 2, 4, 6, . . . such that h = l ·
mf ± k is positive and not a
multiple of 3. For instance, Fig
shows the sixth harmonic (h =
6), which is due to h = 1 · 9 − 2
− 1 = 6.
13
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
28
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf=9):
(i) switch S1current; and
(j) diode D1 current.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
In the linear region (ma ≤ 1) the maximum amplitude of the
fundamental ac output line voltage is √3vi /2. Therefore, one can write
29
To further increase the amplitude of the load voltage, the amplitude of
the modulating signal ˆvc can be made higher than the amplitude of the
carrier signal ˆv, which leads to overmodulation. The relationship
between the amplitude of the fundamental ac output line voltage and
the dc link voltage becomes non-linear
14
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Square-wave Operation of Three-phase VSIs
as
Large values of ma in the
SPWM technique lead to full
is
overmodulation.
This
known
square-wave
The ac line output voltage
operation as illustrated in Fig,
contains the harmonics fh,
where the power valves are
Where h = 6 · k ± 1 (k = 1, 2,
on for 180◦.
3, . . .) and they feature
amplitudes
that are inversely proportional
to their harmonic order
30
(c)ac output voltage; and
(d) ac output voltage spectrum.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
This approach expands the range of the linear region as it allows
the use of modulation indexes ma up to 2/√3 without getting into the
overmodulating region
to
A zero sequence signal is
the modulating
added
they are
signals before
compared
the carrier
signal
31
to
15
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
the
Zero sequence signal generator (ma = 1.0, mf = 9):
(b) modulating signals; and
(c) zero sequence and modulating signals with zero sequence injection.
32
The addition of the zero
the
sequence
reduces
peak amplitude of
the
modulating
resulting
signals (uca , ucb , ucc ),
fundamental
while
components
remain
unchanged
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
The maximum amplitude of the fundamental phase voltage in the linear
region ma ≤ 2/√3 is vi /2, thus, the maximum amplitude of the
fundamental ac output line voltage is vi
33
16
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
VSI. three-phase
The
Ideal
waveforms for the SPWM (ma = 0.8,
mf = 9) with zero sequence signal
injection:
(a) modulating signals;
(b) carrier and modulating signals
with zero sequence signal injection;
34
(c) switch S1 state;
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
35
The
three-phase VSI.
Ideal waveforms for the
SPWM (ma = 0.8, mf = 9)
with zero sequence signal
injection:
(d) ac output voltage;
(e) ac output voltage
spectrum;
17
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
As in single-phase VSIs, the SHE technique can be applied to three-
phase VSIs
36
The harmonics multiples of 3 (h = 3, 9, 15, . . .), could be present in the
phase voltages (vaN , vbN , and vcN ), and will not be present in the
load voltages (vab, vbc , and vca )
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
Thus the chopping angles are used to eliminate only the harmonics
at frequencies h = 5, 7, 11, 13, . . . as required.
37
To eliminate the fifth and seventh harmonics and perform fundamental
magnitude control (N = 3),
18
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
38
Chopping angles for SHE and fundamental voltage
control in three-phase VSIs: fifth and seventh harmonic elimination.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
39
The three-phase VSI. Ideal waveforms for the SHE technique: (a)
phase voltage vaN for fifth and seventh harmonic elimination;
(b) spectrum of (a); (c) line voltage vab for fifth and seventh harmonic
elimination; and (d) spectrum of (c).
19
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế giảm hài bậc 3 trong điện áp pha
40
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Delta Modulation
41
Ia* - Reference current (phase A) ia*
Ia - actual inverter output current (phase A)
ia - error signal (phase A)
20
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1/21/2013
Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện
Delta Modulation
As a result, the actual current ia will be
kept within the upper and lower band limits
Note:
(1) Assume vg1=“1”→G1
If reference current
is
on→ia↑ until t1
sine wave, actual current is
(2) At t1, ia reaches the
also sine wave on which
UBL→vg1=“0”→vg4=“1”→
order
high
some
G4on→ia↓ until t2
are
harmonics
(3) At t2, ia reaches the LBL
→vg1=“1”→vg4=“0”→G1
superimposed. High order
on→ia↑
harmonics can be filtered
out easily.
No low order harmonics.
Inverter output current
can
accurately
controlled
42
be
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện
Delta Modulation
43
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1/21/2013
Power Electronics
For Building
THANK YOU
FOR YOUR ATTENTION
44
22
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22
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Bộ nghịch lưu áp - VSI
23
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf = 9): (a) carrier and modulating signals (b) switch S1 state; (c) switch S3 state; (d) ac output voltage;
11
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Phân tích phổ điện áp dây tải
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf = 9): (d) ac output voltage; (e) ac output voltage spectrum;
24
The harmonics in the ac output voltage appear at normalized frequencies fh centered around mf and its multiples, specifically, at h = l mf ±k l= 1, 2, . . . where l = 1, 3, 5, . . . for k = 2, 4, 6, . . . and l = 2, 4, . . . For k = 1,5, 7, . . . Such that h is not a multiple of 3. Therefore, the harmonics will be at mf ± 2, mf ± 4, . . ., 2mf ± 1, 2mf ± 5, . . ., 3mf ± 2, 3mf ± 4, . . ., 4mf ± 1, 4mf ± 5, . . ..
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp tải
25
12
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Bộ nghịch lưu áp - VSI
Các thành phần hài trong điện áp
26
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phân tích phổ dòng điện DC-link
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf = 9: (g) dc current; (h) dc current spectrum;
27
For nearly sinusoidal ac load current, the harmonics in the dc link current are at frequencies given by h = l mf ± k ± 1 l = 1, 2, . . . where l = 0, 2, 4, . . . for k = 1, 5, 7, . . . and l = 1, 3, 5, . . . for k = 2, 4, 6, . . . such that h = l · mf ± k is positive and not a multiple of 3. For instance, Fig shows the sixth harmonic (h = 6), which is due to h = 1 · 9 − 2 − 1 = 6.
13
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Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
28
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf=9): (i) switch S1current; and (j) diode D1 current.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Điều chế độ rộng xung Sin (SINPWM)
In the linear region (ma ≤ 1) the maximum amplitude of the fundamental ac output line voltage is √3vi /2. Therefore, one can write
29
To further increase the amplitude of the load voltage, the amplitude of the modulating signal ˆvc can be made higher than the amplitude of the carrier signal ˆv, which leads to overmodulation. The relationship between the amplitude of the fundamental ac output line voltage and the dc link voltage becomes non-linear
14
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1/21/2013
Bộ nghịch lưu áp - VSI
Square-wave Operation of Three-phase VSIs
as
Large values of ma in the SPWM technique lead to full is overmodulation. This known square-wave The ac line output voltage operation as illustrated in Fig, contains the harmonics fh, where the power valves are Where h = 6 · k ± 1 (k = 1, 2, on for 180◦. 3, . . .) and they feature amplitudes that are inversely proportional to their harmonic order
30
(c)ac output voltage; and (d) ac output voltage spectrum.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
This approach expands the range of the linear region as it allows the use of modulation indexes ma up to 2/√3 without getting into the overmodulating region
to
A zero sequence signal is the modulating added they are signals before compared the carrier signal
31
to
15
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1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
the
Zero sequence signal generator (ma = 1.0, mf = 9): (b) modulating signals; and (c) zero sequence and modulating signals with zero sequence injection.
32
The addition of the zero the sequence reduces peak amplitude of the modulating resulting signals (uca , ucb , ucc ), fundamental while components remain unchanged
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
The maximum amplitude of the fundamental phase voltage in the linear region ma ≤ 2/√3 is vi /2, thus, the maximum amplitude of the fundamental ac output line voltage is vi
33
16
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1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
VSI. three-phase
The Ideal waveforms for the SPWM (ma = 0.8, mf = 9) with zero sequence signal injection:
(a) modulating signals;
(b) carrier and modulating signals with zero sequence signal injection;
34
(c) switch S1 state;
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
35
The three-phase VSI. Ideal waveforms for the SPWM (ma = 0.8, mf = 9) with zero sequence signal injection: (d) ac output voltage; (e) ac output voltage spectrum;
17
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
As in single-phase VSIs, the SHE technique can be applied to three- phase VSIs
36
The harmonics multiples of 3 (h = 3, 9, 15, . . .), could be present in the phase voltages (vaN , vbN , and vcN ), and will not be present in the load voltages (vab, vbc , and vca )
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
Thus the chopping angles are used to eliminate only the harmonics at frequencies h = 5, 7, 11, 13, . . . as required.
37
To eliminate the fifth and seventh harmonics and perform fundamental magnitude control (N = 3),
18
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Sinusoidal PWM with Zero Sequence Signal Injection
38
Chopping angles for SHE and fundamental voltage control in three-phase VSIs: fifth and seventh harmonic elimination.
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Selective Harmonic Elimination in Three-phase VSIs
39
The three-phase VSI. Ideal waveforms for the SHE technique: (a) phase voltage vaN for fifth and seventh harmonic elimination; (b) spectrum of (a); (c) line voltage vab for fifth and seventh harmonic elimination; and (d) spectrum of (c).
19
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Điều chế giảm hài bậc 3 trong điện áp pha
40
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Delta Modulation
41
Ia* - Reference current (phase A) ia* Ia - actual inverter output current (phase A) ia - error signal (phase A)
20
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện Delta Modulation
As a result, the actual current ia will be kept within the upper and lower band limits
Note: (1) Assume vg1=“1”→G1 If reference current is on→ia↑ until t1 sine wave, actual current is (2) At t1, ia reaches the also sine wave on which UBL→vg1=“0”→vg4=“1”→ order high some G4on→ia↓ until t2 are harmonics (3) At t2, ia reaches the LBL →vg1=“1”→vg4=“0”→G1 superimposed. High order on→ia↑ harmonics can be filtered out easily. No low order harmonics. Inverter output current can accurately controlled
42
be
1/21/2013 PGS.TS Le Minh Phuong
Bộ nghịch lưu áp - VSI
Phương pháp điều chế theo dòng điện Delta Modulation
43
21
1/21/2013 PGS.TS Le Minh Phuong
1/21/2013
Power Electronics
For Building
THANK YOU
FOR YOUR ATTENTION
44
22
1/21/2013
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