INVERTERS: The Investigation to the Presenter: Dr Gawie van der Merwe static as well as mobile applications sinewave inverter range for the use in optimal

INVERTERS: The Investigation to the

Presenter: Dr Gawie van der Merwe

static as well as mobile applicationssinewave inverter range for the use inoptimal topology to the designing of a

Copyright: Dr Gawie van der Merwe www.planmypower.co.za

Background

Investigation towards:– Efficiency– Cost– Reliability– Manufacture (Complexity/Simplicity)

Investigations done in order to search for the optimal topology.

Various Topologies exist.

PV and Mobile Inverters with a sinewave output is the optimal requirement.


Sinewave Inverter Topologies

CVT (Constant Voltage Transformer)50Hz Transformer

– Push Pull Primary- – Full Bridge switching in Primary with series

line Inductor

High Frequency Isolation Transformer and Secondary H-Bridge Control

Series or Parallel Transformer switching


A) Constant Voltage Transformer

SINEWAVE OUTPUT

BATTERY

CVT

Transformer

Inverter “push-pull”

Resonantcomponents

(Ferro Resonant Transformer)


B) 50Hz - Transformer Topology

Various “50Hz” transformer topologies exist

3 Full Bridge Inductor in primary

1 Push-pull - Inductor in primary

2 Push-pull - Inductor in secondary


-10 0 10 20 30

-400

-200

0

200

400

-3

-2

-1

0

1

2

3

TIME (5MS/DIV)

VO

LTA

GE (

V)

CU

RR

EN

T (

A)

CURRENT

VOLTAGE

VOLTAGE AND CURRENTLINEAR LOAD

50Hz TRANSFORMER

-10 0 10 20 30

-400

-200

0

200

400

-8

-6

-4

-2

0

2

4

6

8

TIME (5MS/DIV)

VO

LTA

GE (

V)

CU

RR

EN

T (

A)

CURRENT

VOLTAGE

VOLTAGE AND CURRENTNON-LINEAR LOAD

50Hz TRANSFORMER


Topology B1

SINEWAVE OUTPUT

BATTERY

INDUCTOR

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH

DRIVE CIRCUITAND CONTROLLATCH

TOROID



Topology B1

Disadvantages– Voltage overshoot over devices - leads to

voltage rating increase - Reduction in efficiency

– No-, or limited control over free running inductor current

– “Skewing” of transformer often occur.

Advantages– Simple manufacture & design

– Mosfet drive circuit referred to ground

SINEWAVE OUTPUT

BATTERY

INDUCTOR

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH


TOROID



Primary side Push-pull, series inductor in secondary

SINEWAVE OUTPUT

BATTERY

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH


TOROID

INDUCTOR

Topology B22 Push-pull - Inductor in secondary


Topology B2

Advantages– Simple manufacture & design

– Mosfet drive circuit referred to ground

Disadvantages– Voltage overshoot over devices - leads to

voltage rating increase - Reduction in efficiency

– No-, or limited control over free running inductor current

– “Skewing” of transformer often occur.

SINEWAVE OUTPUT

BATTERY

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH


TOROID

INDUCTOR

2 Push-pull - Inductor in secondary

Copyright: Dr Gawie van der Merwe www.planmypower.co.zaMost popular used topology

SINEWAVE OUTPUT

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH


TOROID

INDUCTOR

BATTERY

Topology B33 Full Bridge Inductor in primary


Advantages– Complete control over primary side inductor

current– Uni-as well as bi-polar pwm control strategy

possible– Simple manufacturing

Topology B3

Disadvantages– System design is more complex– Inverter efficiency is load dependent

SINEWAVE OUTPUT

SINE-REF

FEEDBACK

ERROR AMP

SAWTOOTH


TOROID

INDUCTOR

BATTERY

3 Full Bridge Inductor in primary


C) High Frequency Isolation

SAWTOOTH

TOROID

INDUCTOR

BATTERY

SINEWAVE OUTPUT

ERROR AMP

SINE-REF

FEEDBACKDRIVE CIRCUITAND CONTROLLATCH

PRIMARY SIDE DEVICESCONTROLLED TO OFFERA FIXED DC LINK VOLTAGE


High frequency isolation reduce physical size– Direct output control leads to better

output waveform control and reduced distortion

C) High Frequency Isolation Transformer with full H-bridge Control on Secondary


-10 0 10 20 30-400

-200

0

200

400

-4

-2

0

2

4

TIME (5MS/DIV)

VO

LTA

GE (

V)

CU

RR

EN

T (

A)

CURRENT

VOLTAGE

VOLTAGE AND CURRENTLINEAR LOAD

HIGH FREQUENCY INVERTER

-10 0 10 20 30-400

-200

0

200

400

-6

-4

-2

0

2

4

6

TIME (5MS/DIV)

VO

LTA

GE (

V)

CU

RR

EN

T (

A)

CURRENT

VOLTAGE

VOLTAGE AND CURRENTNON-LINEAR LOAD

HIGH FREQUENCY INVERTER


Advantages– Units generally more mobile– Possible to limit battery current drawn to a

“smooth DC”– Good efficiency with a non linear load

High Frequency Isolation Transformer

Disadvantages– Design is complex– Manufacture is complex– High cost


A wide range of topologies exist

D) Transformer - series and/or parallel switching

A combination of various Transformer switching topologies

– Transformer secondary is in series– Separate output voltage & frequency for

each transformer


BATTERY

(B)(A) (C)

(A+B+C) =

SINEWAVEOUTPUT

Transformer-series and/or parallel switching


-10 0 10 20 30-400

-200

0

200

400

TIME (5MS/DIV)

VO

LTA

GE (

V)

VOLTAGE

VOLTAGE OUTPUT OF MULTI TRANSFORMERINVERTER

MATRIX TRANSFORMER INVERTER

-10 0 10 20 30-400

-200

0

200

400

TIME (5MS/DIV)

VO

LTA

GE (

V)

VOLTAGE

ZOOM INTO VOLTAGE STEPS

MATRIX INVERTER


Advantages– High running to overload ratio is – Very popular design– Advantages for motor startup– High efficiency

Transformer -series and/or parallel switching

Disadvantages– Control complex– Manufacturing is complex– Inverter is big and bulky


Summary

Different topologies have advantages for different applications

Both topology A, B1&B2, (50Hz topology) are outdated

High frequency option, has mobility & weight advantage– Output distortion under all conditions low

Matrix transformer topology– Physical dimensions restrains mobility– Ideal for short period overload power

peak/Mass ratio is good


Estimated Inverter Manufacturing Costs (Same Input Power Stage)

0

1

2

3

4

Th

ou

sa

nd

s

VA

Cost (per u

nit)

300 500 750 1000 1500 3000 5000

QS-INV

HF-SINE

MATRIX SINE

INVERTER MANUFACTURING COST(Based on Linear load)

Input power stage same for comparing Calculation done on continues rating without forced air

cooling Cost calculated on discreet units


Non linear load as a % of total power consumption

Non linear loads - high percentage on power application below 1Kva typical loads, computer, fluorescent lights, video

Higher power application, more resistive, i.e. Microwave, Hairdryer etc. < 1Kva most sensitive to PV applications

0

20

40

60

80

100

POWER INVERTER

LO

AD

PR

OB

AB

ILIT

Y

100 1000 2000 3000

NON-LINEARLOAD LINEAR LOADS

NON LINEAR LOAD AS % OF FULL POWER(TYPICAL APPLICATIONS)


0

2

4

6

8

POWER

SY

STEM

EFFIC

IEN

CY

LO

SS

ES

%

100.00 1000.00 2000.00 3000.00

HF TOPOLOGY

50HZ TOPOLOGY

WEIGHTED % SYSTEM LOSSES AS RESULT OF NON-LINEAR LOAD

(LOSSES DUE TO INVERTER CHOICE)

0 1 2 3 40

5

10

15

20

Thousands

POWER INVERTER (WATT)

EFFIC

IEN

Y L

OS

S (

%)

HF TOPOLOGY

50HZ TOPOLOGY

INVERTER EFFICIENCY LOSS DUE TO NON-LINEAR LOAD

ASSUMPTION 100% LOADSAME POWER STAGE DESIGN


Topology Suggestionsfor Power Levels

Power RatingHigh

FrequencyFull Bridge

50HzMatrix Config.

100-600WMobile (most cost efficient)

50%

Advantage onperm installation

60%

Too expensive

10%

400W-1500WMobile General

70%PV-Permanent

100%PV-Permanent

40%

1000W-2,5Kw PV-Permanent 70%

PV & MobileStackable units

in parallel 70%

PV Permanent

Best choice 80%

2Kw-5Kw

Stackable parallel

combination 100%

Stackable Units

80%Mobile

30%

(Percentage indicates topology choice for the application)

Documents

INVERTERS: The Investigation to the Presenter: Dr Gawie van der Merwe static as well as mobile applications sinewave inverter range for the use in optimal