condizionamento della potenza elettrica a bordo...

Condizionamento della Potenza

Elettrica a Bordo Satellite

Prof. Piero Maranesi, Dr. Federico Belloni, Dr. Marco RivaUniversità degli Studi di MilanoDipartimento di Fisica

P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 2

Space Vehicles

The ISS

LEO satellite (Low Earth Orbit)

Smart – 1 (Earth-Moon mission)

Bepi-Colombo(Mercury exploration)


Power Distribution on the ISS

Scheme of the power distribution system aboard the ISSTotal processed power:110kW


Solar Array

Solar Array of ESA satellite MetOp - 1

ARTEMIS solar array


Solar Power Cell Model

Silicon solar cell electric model

V/I characteristic of a silicon solar module(temperature dependency is reported)

Scheme of a solar array module


Multijunction Solar Cells

Higher efficiency: up to 30% Vs12% of Si Solar Cell


Maximum Power Point Tracking

V

dV

I

dI

IdVVdIIVddP

P

−=⇒

=+==⇒ 0)(max

max

Finding the maximum of IVPSA =

V/I characteristic of a solar array and correspondent power

Commonly used maximum power point trackers are based on the relation


Battery System

Paralleling battery stringBattery pack connected in series

Batteries ensures power availability in case ofpeak power demands and/or eclipses

Modular approach


Battery Voltage Vs Utilized Energy


Unregulated Bus

Usually present on small satellites.Commonly 28VDC unregulated


Regulated Bus

Usually present on medium/large satellites.Commonly 50V, 100V or 120V regulated

BDR: battery discharge regulatorBCR: battery charge regulator


From Main Bus to Loads

Main BUS

DC - DC

Converter

Multi-Output

to analog loads (+/- 12V)

to low voltage supplied circuits (+5V)

Multiphase

Convertersto IC (+3.3V / +1.8V)

Different approaches to the DC – DC converter are adopted for regulated or unregulated buses; depending also on the voltage level


101

102

103

104

105

106

-40

-20

0

20

40

Mag

nitu

de [

dBO

hm]

Input Resistance

101

102

103

104

105

106

-100

0

100

200

Frequency [Hz]

Pha

se [

deg]

Constant Power Loads

0

0)(

0

, <−==⇒

=⇒

=⇒

=

load

load

load

loadloadeq

loadload

load

load

I

V

dI

dVR

VId

dP

constP

Critical typology of load: negative resistance behavior

Closed loop converters are typicalexamples of constant power loads

Experimental measurement of the input resistance of a 5V to 3.3V 50W step down converter

Impedance for ω=0 has a negative value


Negative Resistance and Stability

A simple example

CR

Vin RL

+

-

CRR

RRspole

CsRRRR

R

sV

sVsH

L

Lp

LL

L

IN

C

+−=

++==

:

)(

)()(

If

0]Re[

0

<⇒

>

p

L

s

R

stable system

If

0]Re[

0

>⇒

<

p

L

s

R

unstable system

A load acting like a negative resistance is critic for the dynamic stability.

Stability margins depend on the topology and the control technique of the converter employed


Flyback Converter

Vin

M

T1DT2

Co loadLmag

Single pole dynamics


Phase Shifted Active Full Bridge

Vin

Llk

S6

S5

S4

T1

i

S3

L+

-

T2Co

Vo load

T3

S2

S1

S4,5 ON S3,6 ON S4,5 ONS3,6 ON

S1 ON S2 ONS2 ON S1 ON

1t t2 t 3 t4 t5 t 6 t7T/2 T/2

TT

0

-IL0

IL0 IL

ϕ ϕ

0t t8

=IT1

Commonly used with a regulated bus

Employed onboard the ISSin the 600W version for120V – 28V conversion


Switch in Line Converter - SILC

Vin

120V

C

C

C

C VoVin2

Vo

VoVin2

Vo

T1

T1' L

IL

IT1

S1

S4

S3

S2

D1

D4

D3

D2

Cp1

Cp4

Cp3

Cp2

1

2

3

4

5

6

1.8V - 3.3V

Vout,1

Vout,n

+12VLow drop regulator and

current protection

protectionCurrent +5V

Galvanically isolated

feedback, MOS

controller and drivers

POLsynchronousmultiphaseconverters

Vout,2

Low drop regulator and

current protection

-12V

S1S2S3S4

Inrush currentlimiter

101

102

103

104

105

106

-40

-20

0

20

Mag

nitu

de

[dB

]

Control to Output Voltage

101

102

103

104

105

106

-80

-60

-40

-20

0

20

Frequency [Hz]

Pha

se [

deg]

Phase-shift converter 800W for the 120V regulated bus


A Typical Solution for Unregulated Buses

28V CL

unregulated

Vout,1

Vout,n

Vout,2Step down converter

Push-Pull(isolation stage)

Rectifiers (multioutput)

Voltage regulation is achieved by means of the step down converter

Multi-windings transformers allow a variety of output voltages


Multiphase converters

Vin

5V

1.8V - 3.3V

CL

Phase 1

CL

Phase n

Pµor

CMOS - IC

M11

M21

M1n

M2n

0 TT/n

Vgs (M1i)

t

Phase 1

Phase 2

Phase n

0

0

... ... ... ... ......

n step down converters connected in parallel, each droved with a delay from one to other


Typical Multiphase Scheme

Feedback Network

Controller/Driver

Output Filter

Phase 2 (synchronous buck)

Phase 1(synchronous buck)


The Remote Power Distribution Assembly

for the ISS

Configurable ESA Standard Payload Outfitting Equipment (SPOE) for 120 VDC power distribution and control (manual/remote) within the International Space Station payload racks

Exchangeable Standard Electronic Module


ESEM3 120VDC power distribution & protection(overcurrent)

ESEM2 MIL 1553 data and command I/F .

ESEM5 120VDC power distribution, protection & switch-over

ESEM 1 internal power auxiliary voltages.

ESEM

ESEM4 120VDC – 28VDC conversion stage


Electric Thrusters

Ion Thruster under test

Field Emission Electric Thruster


Radiofrequency Ion Thruster

Typical values:

kWP

mNmNF

cmcmd

VDCVDCV

VDCVDCV

MHzf

thrust

thrust

chamber

eg

bg

rf

5

200/150

22/15

800/150

2000/1500

2/1

==

=

−−=

=

=

High voltages are required to grid supply


High Voltage Generators System

100V

S1

S2

S3

S4

Ls T1

D1

D4

D3

D2

Cadj1

+1500V

S5

S6

S7

S8

T2

D6

D5

D7

Co1

Co2

Currentlimiter

D10

D8

T3

D9

Co3

Co4

Currentlimiter

Ion thruster

Beam grid

Extraction grid

Ds1

100V

S1

Ls

T1D1

D2

D3

Cadj

-800V

T2

D4

Co1

Co2T3

Currentlimiter

S2

Cr

Ds2

Cs

Positive High Voltage Generator

Negative High Voltage Generator

High voltage generators:

PHVG: full bridge phase-shift push-pull converter

NHVG: flyback converter (DCM)

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