Lithium‐ion capacitors (LICs) offer higher energy density and specific energy than do traditional electric double‐layer capacitors (EDLCs). In spacecraft power systems where traditional lithium‐ion batteries (LIBs) have been used with shallow depth of discharge (DoD) in order to achieve long‐cycle life, LICs would potentially be an alternative to secondary batteries. Firstly, this chapter presents the quantitative comparison between the LIB‐ and LIC‐based spacecraft power system from the viewpoint of system mass. On the basis of the potential suggested by the comparison, we have been developing the technology demonstration platform named “NESSIE” that contains the LIC pouch cell as one of its major demonstration missions. NESSIE was successfully launched with the main satellite HISAKI on September 2013. This chapter also presents the development of the LIC pouch cell for NESSIE and its experimental (or ground test) and on‐orbit operation data.
Part of the book: Supercapacitor Design and Applications
The partial shading on a photovoltaic (PV) panel consisting of multiple substrings poses serious issues of decreased energy yield and occurrence of multiple maximum power points (MPPs). Although various kinds of differential power processing (DPP) converters have been proposed to prevent the partial shading issues, multiple switches and/or magnetic components in proportion to the number of substrings are necessary, hence increasing the circuit complexity and volume. This chapter proposes a novel single-switch DPP PWM converter to achieve simplified circuit. The proposed DPP converter is essentially the combination of a forward/flyback resonant inverter (FFRI) and voltage multiplier (VM). The fundamental operation analysis is performed, and the current sensorless control strategy suitable for the proposed DPP converter is also discussed. A 30-W prototype of the proposed DPP converter was built, and various kinds of experimental verification tests were performed emulating partial shading conditions. With the proposed DPP converter, local MPPs of a partially shaded PV panel were successfully eliminated, and energy yield was significantly enhanced, demonstrating the efficacy and performance of the proposed DPP converter.
Part of the book: Solar Panels and Photovoltaic Materials