module-10a ecen 613 rectifier & inverter circuits. prasad enjeti, department of electrical &...

Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University

http://www.ece.tamu.edu/People/bios/benjetip.htmlECEN 613Rectifiers & Inverters

ECEN 613

Rectifier & Inverter Circuits

Professor: Dr. P. Enjeti with Michael T. DanielRm. 024, WEBEmail: [email protected]

[email protected]

Textbook: Power Electronics – Converters, Applications & Design (Third edition), by: Ned Mohan et al., John Wiley

COURSE WEBPAGE: http://eCampus.tamu.edu

Module-10a

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http://enjeti.tamu.eduECEN 613Rectifiers & Inverters

DC-AC Inverters

� Single Phase- Half-bridge Inverter- Full-bridge Inverter- Dual output voltage configuration- Output filter design

� Three Phase Inverter- Dead-time effect

�PWM Techniques- Sinusoidal PWM- Selective harmonic elimination (SHE)- Space vector PWM

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Multilevel Inverters

Reference: L. Helle, S.M. Nielsen, P. Enjeti, “Generalized discontinuous dc-link

balancing modulation strategy for 3-level inverters”, IEEE PCC 2002, pp 359-366

3-level half-bridge



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Multilevel Inverters - NPC3-level half-bridge neutral point clamped (NPC)

Reference: A. Nabae, I. Takahashi, H. Akagi, “A new neutral-point clamped

PWM inverter”, IEEE Transactions on Industry Applications, Sep/Oct 1981, pp

518-523

Gating signals

Output voltage waveforms



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Multilevel InvertersDC-Link capacitor voltage balancing issues - analysis

To reduce neutral-point voltage

deviation, the dwell time of a given small vector can be

equally distributed between the P-type and N-type

switching states over a sampling period.



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Space Vector PWM for NPC

• Each inverter leg has 3 switching states which results is 27 voltage vectors. No power is delivered to the load for

switching states 111, 000 and -1-1-1 and are referred to as zero voltage vectors.

• A total of 6 states exists that result is in identical output voltage vectors. Such as 110 and 00-1.

• Therefore there are 18 effective voltage vectors and 1 zero vector. The non zero voltage vectors can have three

phase voltage levels which are: LV, MV, SV



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Multilevel Inverters

Reference: D.M. Lee, J.W Jung, S.S. Kwak, “Simple space vector PWM scheme

for 3-level NPC inverters including the overmodulation region”, Journal of

power electronics, Sep 2011, pp 668-696



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Multilevel Inverters : 5-level

For a m-level inverter we have:

• Number of switches = 2(m-1)

• Number of dc-link capacitors = (m-1)

• Number of clamped diodes = 2(m-2)

• Voltage across each dc-link capacitor = ��

��

Van



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Multilevel Inverters - ABB



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Multilevel Inverter based on the H-Bridge Inverters

1-phase topology

Output phase voltage waveform of a 11-level cascaded inverter with 5 separate dc

sources

Note: Each cell delivers different power



A

oa1

oa2

oa3

oa4

a1

a1'

a2

a2'

a3

a3'

a4

a4'

Inv. 1a

Inv. 2a

Inv. 3a

Inv. 4a

Multilevel PWM Generation with 1-phase Inverter Cells (H-bridge)



A

oa1

oa2

oa3

oa4

a1

a1'

a2

a2'

a3

a3'

a4

a4'

Inv. 1a

Inv. 2a

Inv. 3a

Inv. 4a

Multilevel PWM Generation with 1-phase Inverter Cells



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Medium Voltage Adjustable Speed AC Motor Drive: ASI-Robicon – Perfect Harmony

b

c

a

A B C

ib

ic

ia

oa1

oa2

oa3

oa4

a1

a1'

a2

a2'

a3

a3'

a4

a4'

b2

b2'

b1

b1'

b3

b3'

b4

b4'

c1

c1'

c2

c2'

c3

c3'

c4

c4'

for simplicity

M

+22.5o

+7.5o

-7.5o

-22.5o

na1

na2

na3

na4

Inv. 1a

Inv. 2a

Inv. 3a

Inv. 4a

Inv. 1b

Inv. 2b

Inv. 3b

Inv. 4b

Inv. 1c

Inv. 2c

Inv. 3c

Inv. 4c

• Input current and output voltage is of high quality

• Complicated multi-winding 60Hz input transformer

• Single phase inverter dc-link capacitor size is large

• Modular in construction & employs low voltage devices



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Toshiba MV Drive

Circuit Topology

Mixed level hybrid unit configuration using H-bridge NPC cascaded

converter cell to increase voltage levels



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Toshiba MV Drive



Hybrid Multilevel Inverter based on the H-Bridge Inverters

Reference: M. Manjrekar, P. Steimer, T. Lipo, “Hybrid multilevel power conversion system: a compatetive solution for high-power applications”, IEEE Transactions

on Industry Applications, May/June 2000, pp 834-841



Hybrid Multilevel Inverter based on the H-Bridge Inverters



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Multilevel Inverters - Flying Capacitor

Van= E , S1 S2 on Van= - E , S1’ S2

’ on

Van= 0, S2 S2’ on Van= 0, S1 S1

’ on

Note: S1 S2’ and S2 S1

’ are gated complimentary



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Multilevel Inverters - Flying Capacitor



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A Generalized Multilevel Inverter Topology

module-10a ecen 613 rectifier & inverter circuits. prasad enjeti, department of electrical &...

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