The European Space Agency Tender

Some New Li-ion Batteries Have A Very Flat Iv (current-voltage) Curve. Thus, As They Are Discharged The Voltage Stays Very Flat. The Classical Method To Measure The State Of Charge (soc) Was Simply To Measure The Voltage. However, This Is More Complicated Now Because There Is Not A Big Change In Voltage. Therefore, It Is Not Possible To Accurately Estimate The Soc. This Has Very Critical System Level Implications. A High Battery Discharge Typically Triggers An Fdir (fault Detection, Isolation And Recovery) Process To Reconfigure The Spacecraft, Go To Safe Mode And Be Sun Pointed. If The Soc Is Not Accurately Estimated, There Could Be No Remaining Energy In The Battery To Perform This Critical Manoeuvre.some Satellites Are Already Suffering This Issue And Workarounds Are Being Discussed. Therefore, It Has Been Identified The Need To Understand How To Really Measure The Soc To Implement A Reliable System.the Proposed Activity Aims At Assessing Various Methods To Achieve The Above, In Coordination With Battery Manufacturers. The Various Methods Have To Be Implemented In An Electronic Circuit, Aiming At Minimising The Complexity While Having A Good Accuracy. The Various Methods Should Then Be Tested To Understand The Real Accuracy Of The System To Select The Most Adequate One.as A Minimum, The Following Methods Shall Be Assessed:modelling Of The Battery Performance In An On-board Fpga (field-programmable Gate Array).very High Accuracy Voltage Sensing.in/out Coulomb Counting.battery Internal Impedance Estimation.the Following Tasks Are Foreseen Inthe Frame Of This Activity:review The State-of-the-art Systems To Estimate State Of Charge.analyse The Most Promising Methods.trade-off The Best Possible Candidate.design The Soc Estimator System.build A Breadboard Of The Soc Estimation System.test The Circuit.note: This Activity Is Currently In The Gstp Work Plan But Will Only Be Implemented After Confirmation Of Financial Support From Delegations. The Final List Of Participating States Will Be Known At Tender Issue.