With advancements in vehicle electrification and the integration of electronic controls, vehicle computers and electronics are using increasingly more power. Today, the electronic components comprising the power circuits of vehicle electronics require technological innovation. TAIYO YUDEN and its 100% subsidiary ELNA are engaged in the development and provision of conductive polymer hybrid aluminum electrolytic capacitors. Through these new products, they are contributing to the development of the automotive industry by promoting greater efficiency and size reduction for the power sources that provide compatibility for high-power applications.
From windshield wipers and power windows to the basic functions of run, turn, and stop, all the mechanisms in vehicles today are precision controlled by advanced on-board computers. Additionally, recent years have seen the adoption of advanced driver assistance systems (ADAS), which take advantage of state-of-the-art information processing technology. And in the near future, it is projected that markets will progress towards autonomous vehicles and software defined vehicles (SDV), which use software to achieve high-value-added vehicle functions.
With advancements in electrification and electronic controls, modern vehicles, which are often referred to as “computers on wheels,” evolve to become “mobile data centers.” This evolution is what will likely lead to the integration of high-performance on-board computers, networking equipment, and other vehicle electronics that are driven by motors with higher output than have ever been used before.
Generally speaking, such advancements in the functionality of vehicle electronics tends to involve massive power consumption. As such, this also means there is a need for power circuits capable of higher efficiency and more stable power provision. However, we have reached a point where the electronic components comprising existing power circuits are no longer capable of fully meeting the technological parameters demanded by next-generation vehicles. This evolution in vehicles is creating the need for technical innovation for the electronic components used in the power circuits of vehicle electronics.
“We have expanded our line of new conductive polymer hybrid aluminum electrolytic capacitors (below, hybrid capacitors) to contribute to higher reliability, longer service life, greater efficiency, and smaller sizes for the power circuits providing compatibility for the increasing power needs of vehicle electronics,” says Tadahiro Nakamura of ELNA, a subsidiary of TAIYO YUDEN.
With capacitors and other electronic components comprising the power circuits used in vehicle electronics, it is necessary to select products that provide high reliability, a long service life, and achieve high efficiency. With the increasing high-performance characteristics of vehicle electronics, the technical requirements applied to these electronic components are only increasing.
“Generally speaking, multilayer ceramic capacitors (MLCC) and aluminum electrolytic capacitors, which are more suited for high-voltage, high capacitance applications, are selected as the capacitors used in the circuits of vehicle electronics. However, due to structural characteristics, there is no more room for improving the performance of aluminum electrolytic capacitors and the industry has reached a point where it is becoming difficult to achieve the properties necessary to keep up with advancements in the performance of vehicle electronics,” says Nakamura.
The power circuits of vehicle electronics also use switch power sources. This is driving a trend towards increasing the switching frequency in order to promote greater efficiency and size reductions. There are already cases of power circuits operating at 100kHz or higher being used. With circuits that incorporate power semiconductors made using the next-generation material gallium nitride semiconductor (GaN), applications operating at 1MHz are also possible. At present, apparently it is not possible to use aluminum electrolyte capacitors for such applications.
“The electrolytes used in hybrid capacitors combines a conventional electrolyte liquid and a conductive polymer with a lower resistance. This makes it possible to reduce equivalent series resistance (ESR) at a broader frequency band and temperature range when compared to aluminum electrolytic capacitors. ESR is one of the indicators used to judge capacitor electrical characteristics and reliability performance. Capacitors with a low ESR value provide favorable smoothing and transient response characteristics in power circuits, which leads to more stable power output. These capacitors provide superior characteristics, such as absorbing noise at high frequencies, making it possible to respond to demands placed on vehicle power circuits” (Nakamura).
Achievable characteristics vary greatly depending on the materials and structures comprising a capacitor. Hybrid capacitors operate at high switching frequencies and their characteristics offer compatibility with power circuits used in applications involving relatively high-voltage electricity. These characteristics are aligned with the demands being placed on the next generation of vehicle electronics.
There are also conductive polymer capacitors that only use a conductive polymer as the electrolyte. However, with these capacitors, it is difficult to achieve a long service life at high voltages so they are not seen as being ideal for use in vehicle electronics. In the event of oxidative defects in the aluminum oxide film comprising the dielectric material, there is no electrolyte so self-repair is not possible. This makes it difficult to use these capacitors in vehicle electronics for which reliability is a critical factor. However, the service life of hybrid capacitors can be extended because they have the ability to use the electrolyte to conduct self-repair of oxidative defects. This same characteristic also means a reduction in leakage current.
Hybrid capacitors are a relatively new type of capacitor for which the technology was established in the 2010s. However, applications capable of utilizing the characteristics of these capacitors have been limited. With the trend towards high-performance vehicle electronics, demand has grown for capacitors that can be used at higher frequencies than aluminum electrolytic capacitors while also offering compatibility for higher voltages than conductive polymer capacitors. “Today, hybrid capacitors are garnering attention as capacitors that meet the needs of today,” says Nakamura.
Hybrid capacitors combine a conventional electrolyte with a low-resistance conductive polymer for the electrolyte. This allows manufacturers to take advantage of the merits of both types of capacitors: the high-voltage properties of aluminum electrolytic capacitors and the high-frequency compatibility of conductive polymer capacitors.
“Global original equipment manufacturers (OEM) and tier-1 companies have already decided to use hybrid capacitors in the power circuits of vehicles being launched to market moving forward,” states Nakamura. TAIYO YUDEN is projecting that hybrid capacitor demand will increase rapidly to roughly 2.5x by 2025 and nearly 5.1x by 2030 compared to 2020 volume. For capacitor manufacturers, quickly establishing development and provision structures for products meeting the specification demands of user companies is an urgent issue.
“Our strength lies in our vast product selection. In particular, you could say we are leading the competition in providing high capacitance products. Using capacitors with a higher capacitance enables circuit size reduction and design simplification compared to designs based on multiple low-capacitance products. We offer various types to meet the needs of various use cases, including our HVK Series of high-temperature products and the HT and HTK Series of products that offer strong vibration resistance,” states Nakamura.
The ability to offer this vast selection of products is due to TAIYO YUDEN’s long track record of supplying products to numerous customers in the domain of capacitors for vehicle electronics. This strong connection with customers enables them to lead the market in responding to future capacitor specification requirements.
“From development to production, we do everything in Japan and have established a business structure that enables rapid and appropriate collaboration between development and production for the materials and elemental structures that comprise capacitors. In turn, this enables us to deliver products with the characteristics required by the automotive industry ahead of the competition. We will continue to expand our production structure in line with increasing demand,” notes Nakamura.
Dramatic leaps in power circuit performance not possible using conventional capacitors. This is made possible by using hybrid capacitors, and the potential use cases are sure to increase moving forward. If you are striving for technological innovation in your power circuits, then perhaps you should take a look at hybrid capacitors.