Bi-Directional Supercap Charger Integrates Backup & Balancing

July 30, 2015 // By Christoph Hammerschmidt
A supercapacitor (also known as an SCAP, supercap, double-layer capacitor, or ultracapacitor) is more than just a capacitor with a very high level of capacitance. Compared to standard ceramic, tantalum or electrolytic capacitors, supercaps offer higher energy density and higher capacitance in a similar form factor and weight. As the cost to produce them continues to decline and as the market gets exposed to their capabilities, supercapacitors are carving out an ever-growing niche between conventional capacitors and batteries.

Although supercaps require some “care and feeding,” they are augmenting (as a complementary power source to reduce strain on the primary source, thereby extending its life) – or even replacing - batteries in data storage applications requiring high current/short duration backup power. Furthermore, they are also finding use in a variety of high peak power and portable applications in need of high current bursts or momentary battery backup, such as UPS (uninterruptible power supply) systems. Compared to batteries, supercaps provide higher peak power bursts in smaller form factors and feature longer charge cycle life over a wider operating temperature range. Supercap lifetime can be maximized by reducing the capacitor’s top-off voltage and avoiding high temperatures (>50°C). See Figure 1 for energy density capability and Table 1 for a comparison to alternatives.

Figure 1. Storage Element Energy Density vs. Power Density

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