1 Evaluation of Power Control System for Micro and Nano Satellites by Hardware-in-the-Loop Simulator

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1 1 Evaluation of Power Control System for Micro and Nano Satellites by Hardware-in-the-Loop Simulator Yuji Sakamoto, Toshinori Kuwahara, et al. Tohoku University, Japan 16 AUG 2012 Small Satellite Conference UTAH, US

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3 Background 3 SPRITE-SAT (RISING), Tohoku University 1st satellite JAN 2009, launched and started operation defects of battery charge and discharge H/W control a lot of efforts for power system evaluation were being devoted after following satellites

4 battery voltage (V) battery voltage (V) battery temperature (degc) Charging history 4 voltage temp. environment 20 degc Discharging history battery capacity (%) environment 20 degc battery capacity (%) from catalogue of SANYO Twicell(R)

5 5 Charging was not stopped at the full capacity capacity was manually controlled by On/Off of instruments because of shade by mast, output from one solar panel was decreased charging was decreased, and critical low voltage was occurred At present, the telemetry signals are not modulated (0.1W CW signals can be monitored) data handling system is defective (estimated)

Objectives 6 Using Hardware in the Loop (HIL) simulator, power system is evaluated in system level Utilized for developing RISING-2 and RAIKO Solar generation power and bus

6 Objectives 6 Using Hardware in the Loop (HIL) simulator, power system is evaluated in system level Utilized for developing RISING-2 and RAIKO Solar generation power and bus consuming power are supplied or consumed by external equipment onboard power status is monitored by telemetry data results are compared to software simulator, then the math model is improved

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5 km) (C)Google High Precision Telescope

8 Spec. of RISING-2 Size: 50x50x50 cm Mass: 41 kg Orbit: SSO, 628-km alt., launched in m reso. ground photo cumulonimbus clouds Sprite, terrestrial lightning events around Sendai Sta. (3.3 x 2.5 km) (C)Google High Precision Telescope (HPT) - 5-m resolution telescope with ZPF mirror - 10-cm diameter, 1-m focal length - RGB and Multi-spectrum CCDs incl. of LCTF (liquid crystal tunable filter) Bolometer Array (BOL) FOV = 29 deg Wide Field CCD (WFC) FOV = 134x180deg Lightning and Sprite CMOS Imager (LSI) - 1st CMOS (762nm) - 2nd CMOS ( nm) - FOV = 27x27 deg

9 9 ACU Attitude Control Unit SCU Satellite Central Unit SHU Science Handling Unit PCU Power Control Unit

10 System-level electrical test 10 satellite (EM) dummy solar power dummy ground station (transmitter and receiver for ground station) ground operation software

11 Word, Excel specification documents development of C&DH system Quick-Look software (ground operation soft) 11 Visual C# FPGA coding (VHDL) Xilinx ISE CPU coding (C, C++) Renesus HEW

12 (6) 12 (1) (3) (2) (4) (5)

13 OLD ground operation software for 1st satellite SPRITE-SAT 13 difficult to recognize the status and troubles

14 Specs of power system 14 RISING-2 power generation effi. 27.1% of solar cells body mound solar panels 8-series and 4-pallarel (18.64V, 452mA) for each panel, or 8-series and 2-pallarel(18.64V, 226mA), total 5 panels 41.1W generation power in no-controlled spin motion industrial grade NiMH batteries, 9-series and 1-parallel (discharge 10.8V avg, 3700mAh) NiMH battery is safe and few risks charging is automatically stopped by monitoring voltage and temperature. the setting parameters can be changed by ground commands

15 solar panel simulator (agilent corp. E4350B) 15

16 electrical load (KIKUSUI PLZ164WA) 16

17 17 RF Transmitter A. Satellite (REAL) Data Handling Unit Power Control Unit RF Telemetry Receiver telemetry Solar Panel (Dummy) Load (Dummy) a. Operation Software (for REAL) desktop PC #1 SIGNAL POWER H/W S/W HILS equipment command B. Satellite (Simulator) b. Operation Software (for Simulator) desktop PC #2 telemetry

18 DEMO 18

19 Software Simulator 19 aspects of Software in the Loop(SILS) simulator in the combination of SatSimulator and ground operation software, the estimated status of dummy satellite can be checked in addition to real-time mode (125-ms period), the fast mode (speed is up to computer) can be available. the simulations with various conditions can be evaluated quickly 1: Orbit & Attitude Simulator calculating the orbit and attitude updating status of orbit, attitude, solar cells, magnetometer, and so on

20 Software Simulator 20 2: coarse control by onboard computer magnetic coils control by update values of solar cells and magnetometers 3: calculation in power control unit decide the battery charging or discharging mode from the comparison of bus consuming power and solar generation power decide the voltage and current of solar panels and batteries from the math models adopting the power converting efficiency or power loss (70% is suitable in the first stage)

21 BAT-SOC Power (%) (W) Power (W) Bus P. MIN 12.03, MAX W Bus Power & Solar Power (RISING-2) Solar P. MAX W REAL Evaluation Results (bus power, solar power) time after start of eclipse (min) Bus 20 Power 30 & 40 Solar 50 Power 60 (RISING-2) Bus P. MIN 11.90, MAX W Solar P. MAX W Battery State of Charge MIN = 67.5 % (DOD 32.5 %) time time after after start start of of eclipse eclipse (min) (min) SIM REAL Hardware (EM) observation mode of 32-W cosumption are carried out in 15 min each in sunshine and eclipse 12W consuming in other periods Soft. Simulator eclipse ( min) sunshine ( min) MODE-A0 (0-10min) MODE-A4 (10-15min) MODE-S6 (15-25min) MODE-A0 (25-60min) MODE-A4 (60-65min) MODE-S6 (65-75min) MODE-A0 (75-min) 35-min eclipse -> 62-min sunshine

22 BAT-SOC T.C.BAT-V (%) (V) T.C.BAT-V (V) (Temp. Comp. battery voltage) Temp. Comp. Battery Voltage (RISING-2) REAL TERM-V (13.13V) at 85.9 min time after start of eclipse (min) Temp. Comp. Battery Voltage (RISING-2) Battery State of Charge SIM TERM-V (13.13V) at 77.5 min MIN = 67.5 % (DOD 32.5 %) time after start of eclipse (min) MAX = V MIN = V REAL MAX = V MIN = V Hardware (EM) Soft. Simulator eclipse ( min) sunshine ( min) MODE-A0 (0-10min) MODE-A4 (10-15min) MODE-S6 (15-25min) MODE-A0 (25-60min) MODE-A4 (60-65min) MODE-S6 (65-75min) MODE-A0 (75-min)

23 BAT-SOC (%) BAT-SOC (%) (Battery State-of-charge) MODE-A0 (0-10min) Battery State of Charge MIN = 67.5 % (DOD 32.5 %) time after start of eclipse (min) MODE-A4 (10-15min) eclipse ( min) sunshine ( min) Battery State of Charge (RISING-2) MODE-S6 (15-25min) MIN = 69.8 % (DOD 30.2 %) MODE-A0 (25-60min) MODE-A4 (60-65min) time after start of eclipse (min) MODE-S6 (65-75min) REAL MODE-A0 (75-min) eclipse ( min) sunshine ( min) SIM Hardware (EM) Soft. Simulator MODE-A0 (0-10min) MODE-A4 (10-15min) MODE-S6 (15-25min) MODE-A0 (25-60min) MODE-A4 (60-65min) MODE-S6 (65-75min) MODE-A0 (75-min)

24 Cubesat RAIKO 24 by team of Wakayama Univ. and Tohoku Univ. 2.6-kg 2U size Cubesat Using spin-off technologies from 50-kg micro satellites Now in International Space Station Will be released in September (planned)

Features Cubesat RAIKO 25 1) by total 3 cameras, the photos of ISS, Earth, and stars are obtained

orbit, total 46 photos of ISS are taken * photos can be taken at anywhere in globe by task

2GHz data transmitter, 13GHz data transmitter and 13GHz beacon transmitter 3) 50-cm rectangle

25 Features Cubesat RAIKO 25 1) by total 3 cameras, the photos of ISS, Earth, and stars are obtained * color wide-view CMOS, color fish-eye CCD, and mono CCD * in 30-min after satellite release to orbit, total 46 photos of ISS are taken * photos can be taken at anywhere in globe by task schedule commands 2) high-rate telemetry communication (38.4kbps nom. to 500kbps max.) * 2.2GHz data transmitter, 13GHz data transmitter and 13GHz beacon transmitter 3) 50-cm rectangle thin film is deployed at 300-km alt. for de-orbit experiment inside of sat. test phote by fish-eye CCD deployable film

26 Spec of power system 26 RAIKO solar power generation effi % (from catalogue) 2-series and 1-pallarel (4.82V, 438mA) for each panel, total 6 panels (12 cells) total 10 panels when 2 paddles are opened 3.19W power generation in no-control spin motion when paddle closed, and 4.70W when paddle opened batteries are commercial NiMH (eneloop), 8-series and 1- parallel (discharge 9.6V avg, 750mAh)

27 BAT-SOC (%) Power (W) (bus power, solar power) 5 SIM Bus P. MIN 0.71, MAX 4.56 W Bus Power & Solar Power (RAIKO) Solar P. MAX 4.93 W circle orbit 51.6-deg incl. 300-km alt. 2.0-deg/s spin 27 (SOC) time after start of eclipse (min) Battery State of Charge (RAIKO) Soft. Simulator SIM MIN = 92.6 % (DOD 7.4 %) time after start of eclipse (min) eclipse ( min) sunshine ( min) circle orbit 51.6-deg incl. 300-km alt. 2.0-deg/s spin Soft. Simulator MODE-S/B (0-59min) MODE-COMM (59-67min) MODE-S/B ( min)

28 Conclusions 28 Using hardware and software simulators, the health of system can be estimated in long time span before and after the launch defectives can be found long-time evaluation of battery performance quick evaluation of power system before and after environmental tests After the launch, using software simulator including the improved math model, future power status can be estimated correctly (nominal case, and especially emergency case)

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