Condizionamento della Potenza Elettrica a Bordo Satellite

Transcription

1 Condizionamento della Potenza Elettrica a Bordo Satellite Prof. Piero Maranesi, Dr. Federico Belloni, Dr. Marco Riva Università degli Studi di Milano Dipartimento di Fisica

2 Space Vehicles LEO satellite (Low Earth Orbit) The ISS Bepi-Colombo (Mercury exploration) Smart 1 (Earth-Moon mission) P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 2

3 Power Distribution on the ISS Scheme of the power distribution system aboard the ISS Total processed power:110kw P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 3

4 Solar Array Solar Array of ESA satellite MetOp - 1 ARTEMIS solar array P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 4

5 Solar Power Cell Model Silicon solar cell electric model Scheme of a solar array module V/I characteristic of a silicon solar module (temperature dependency is reported) P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 5

6 Multijunction Solar Cells Higher efficiency: up to 30% Vs 12% of Si Solar Cell P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 6

7 Maximum Power Point Tracking Finding the maximum of P SA = IV Commonly used maximum power point trackers are based on the relation P max dp = d( IV ) = VdI + IdV = 0 di I max = dv V V/I characteristic of a solar array and correspondent power P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 7

8 Battery System Batteries ensures power availability in case of peak power demands and/or eclipses Modular approach Paralleling battery string Battery pack connected in series P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 8

9 Battery Voltage Vs Utilized Energy P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 9

10 Unregulated Bus Usually present on small satellites. Commonly 28VDC unregulated P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 10

11 Regulated Bus Usually present on medium/large satellites. Commonly 50V, 100V or 120V regulated BDR: battery discharge regulator BCR: battery charge regulator P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 11

12 From Main Bus to Loads Main BUS DC - DC Multi-Output to analog loads (+/- 12V) to low voltage supplied circuits (+5V) Converter Multiphase Converters to 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 P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 12

13 Constant Power Loads Critical typology of load: negative resistance behavior P load dp d( I R = const load load = 0 V load ) = 0 dv load load eq, load = = < diload Iload Closed loop converters are typical examples of constant power loads V 0 Impedance for ω=0 has a negative value Magnitude [dbohm] Phase [deg] Experimental measurement of the input resistance of a 5V to 3.3V 50W step down converter Input Resistance Frequency [Hz] P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 13

14 Negative Resistance and Stability Vin A simple example + - R C R L If R L H ( s) V = V pole : > 0 Re[ s p C IN ( s) = ( s) s ] < 0 p = R + R R + RL RR C L L RL + srr If R L L C < 0 Re[ s p ] > 0 stable system 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 P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 14

15 Flyback Converter Lmag T1 T2 D Co load Vin Single pole dynamics M P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 15

16 Phase Shifted Active Full Bridge Commonly used with a regulated bus Vin + - S6 S5 i L Llk T1 S3 S4 T2 T3 S2 Co Vo load Employed onboard the ISS in the 600W version for 120V 28V conversion S1 t1 t 2 t 3 t 4 t 5 t 6 t 0 7 T/2 T/2 t t 8 Tϕ Tϕ S3,6 ON S4,5 ON S3,6 ON S4,5 ON S1 ON S2 ON S1 ON S2 ON I L0 I L =IT1 0 -I L0 P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 16

17 Switch in Line Converter - SILC 120V V in C C C C Inrush current limiter 6 5 V in 2 V in 2 V o V o V o T 1 ' V o T 1 Cp4 I L L Cp3 Cp2 I T1 Cp1 4 D4 3 D3 2 D2 1 D1 S1 S2 S3 S4 S4 S3 S2 S1 Galvanically isolated feedback, MOS controller and drivers V out,n V out,1 V out,2 Low drop regulator and current protection Low drop regulator and current protection Current +5V protection POL synchronous multiphase converters +12V -12V 1.8V - 3.3V Magnitude [db] Phase-shift converter 800W for the 120V regulated bus Control to Output Voltage Phase [deg] Frequency [Hz] P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 17

18 A Typical Solution for Unregulated Buses 28V unregulated L C V out,1 Step down converter V out,2 Push-Pull (isolation stage) V out,n Rectifiers (multioutput) Voltage regulation is achieved by means of the step down converter Multi-windings transformers allow a variety of output voltages P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 18

19 Multiphase converters Phase 1 M11 M21 L C 1.8V - 3.3V µp or CMOS - IC Vgs (M1i) Phase n Phase 1 M1n L C Phase 2 0 V in 5V M2n n step down converters connected in parallel, each droved with a delay from one to other Phase n 0 T/n T t P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 19

20 Typical Multiphase Scheme Phase 1 (synchronous buck) Output Filter Feedback Network Phase 2 (synchronous buck) Controller/Driver P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 20

21 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 P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 21

22 ESEM ESEM 1 internal power auxiliary voltages. ESEM2 MIL 1553 data and command I/F. ESEM3 120VDC power distribution & protection (overcurrent) ESEM4 120VDC 28VDC conversion stage ESEM5 120VDC power distribution, protection & switch-over P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 22

23 Electric Thrusters Ion Thruster under test Field Emission Electric Thruster P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 23

24 Radiofrequency Ion Thruster f V V d F P Typical values: rf bg eg = 1/ 2MHz = 1500VDC / 2000VDC = 150VDC / 800VDC chamber thrust thrust = 15cm / 22cm = 150mN / 200mN = 5kW High voltages are required to grid supply P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 24

25 High Voltage Generators System Positive High Voltage Generator 100V S2 S1 D1 Ls D2 T1 D3 D4 S3 S4 S5 S6 D8 D9 D5 T3 Co3 Co4 Current limiter Co1 D10 Cadj V High voltage generators: PHVG: full bridge phase-shift pushpull converter T2 D7 NHVG: flyback converter (DCM) S7 Co2 D6 S8 Current limiter Beam grid 100V D1 Ls T1 Ds2 Cs T2 D2 Co1 Current limiter Cadj Extraction grid Ion thruster Cr S2 Ds1 T3 D3 Co2 D4-800V S1 Negative High Voltage Generator P.G. Maranesi Condizionamento della potenza elettrica a bordo satellite 25