ISO/TR 20891:2020 宇宙システム—宇宙電池—リチウムイオン電池の飛行中の健康評価のためのガイドライン | ページ 2

3.1 用語と定義

この文書の目的としては、ISO 17546 および以下に示されている用語と定義が適用されます。

ISO と IEC は、標準化に使用する用語データベースを次のアドレスで維持しています。

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives ).

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents ).

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This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 14, Space systems and operations.

Introduction

The charge and discharge cycle of a battery is not 100 % efficient, with each cycle side reactions can occur that eventually accumulate and cause degradation of the battery's performance. Understanding how the battery’s performance changes throughout the mission is a subject of importance; and accurate determination of the battery’s current SoH is essential in a large number of situations, for example:

• the routine assessment of battery performance to allow early detection of anomalies (by comparing its actual versus predicted performance);
• the setting of alarm thresholds to ensure adequate energy;
• detection of battery anomalies that can put at risk the spacecraft passivation and/or de-orbiting strategy;
• decisions regarding mission extension beyond initial target life;
• evaluating the remaining capability of a spacecraft upon occurrence of an anomaly;
• feedback to the battery manufacturer to improve the performance predictions.

However, it is often difficult to properly assess the in-flight status, due to various factors:

• Flight electrical load profiles differ significantly to load profiles used to characterize battery performance models and the battery’s SoH; for example, the total available battery capacity, which is the most important parameter, is not directly accessible during flight since its simple measurement by full discharge of the battery goes against the spacecraft operational safety.
• The quality of the accessible data from telemetry is sometimes poor: insufficient telemetry resolution and/or accuracy, lack of synchronization between related parameters like current and voltage, possibly large load consumption fluctuations introducing a high level of noise, delivery of data under a form not easy to process, etc.
• The battery is operating in flight in a way that is generally very different from the test conditions at qualification or acceptance. As a consequence, if no in-flight assessment has been made at the beginning of life, the direct comparison between current in-flight status and available ground testing data can be difficult and in any case more difficult than a comparison with the initial in-flight behaviour.
• The battery is operated under time variant conditions in a large bandwidth of different time scales, e.g. switching heater circuits vs. variations of the charge profile and eclipse length for a LEO satellite with drifting orbit. Low frequency variations introduced by drifting orbits or seasons are considered for the computation of trends and averaging over several orbits.
• The processing of data to derive the health status is not straightforward and is usually performed by identifying the ageing parameters of a model. Therefore, the representativeness of this model is a key issue. In addition, even with a good model, the results are not always satisfactory.

Therefore, it has been found of interest to provide detailed information about the means currently used or envisioned to perform in-flight battery health assessment and to make recommendations to spacecraft builders, operation managers and batteries manufacturers that would make it easier. This is the subject of this document.

It is important to highlight that, according to the definition given in 3.1.1, assessing the health status allows to verify that the battery behaves as well as or possibly better than anticipated. It is not aimed at providing an evaluation of any sort of “absolute ageing” nor to predict further evolution, even if this can be the case with some methods and their on-board implementation.

1 Scope

This document provides detailed information on the various methods of assessing the health status of lithium-ion space batteries in flight and makes recommendations to battery suppliers, spacecraft manufacturers and operators to ease this assessment.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms, definitions and abbreviated terms

3.2 Abbreviated terms

Bibliography