Technical Library

Latest Technology Trends in Capacitors
for the EV, HV and PHV Markets

NICHICON CORPORATION

Nichicon anticipates dramatic changes in a variety of sectors due to the acceleration of IoT throughout society. In addition to advanced driver assistance systems (ADAS) in the automotive market and self-driving cars, attention is turning to connected cars that provide an added level of comfort. Nichicon believes its proposal of capacitors for electrical systems in self-driving cars and infrastructure-related devices will help further these developments. To this end, we introduce the latest technology trends in capacitors for a variety of sectors.

■Latest Technology Trends in Film Capacitors for Motor Drive Units
Film capacitors for motor drive units in electric (EV), hybrid (HV) and plug-in hybrid (PHV) vehicles mainly use polypropylene film. These capacitors each have a dielectric with a thickness of several µm, as well as a vapor-deposited metalized film with a metal membrane pattern on their surfaces. The result is a set of excellent electrical properties, including high levels of safety and reliability.
 Film capacitors for motor drive units must be small, long-lasting, and inexpensive, which requires integrated product development from materials development to optimal structure design.

  • (1) Miniaturization via thin dielectric film

  • Thin dielectric film is essential, as film capacitor volume is nearly proportional to the square of the film thickness. Currently, 2.5-μm polypropylene film is predominantly mass-produced, but the development of even thinner film is advancing for next-generation systems.

  • (2) Development of vapor-deposition technologies for higher voltage-withstanding
    and longer life

  • As films become thinner, voltage withstanding must improve. Patterns formed on vapor-deposited metal become electrodes; these are divided into small segments, with each small segment connected to a fuse element. This feature maintains security, and establishes a high degree of safety, and ensures higher voltage withstanding and longer life.

  • (3) Structural design optimization

  • In recent years, developments in analytical techniques based on the finite element method have made it possible to predict film capacitor performance from the theoretical valuation stage. In addition to conventional strength design, it is possible to optimize structural design from the early stages of development by improving analysis accuracy—even in low inductance and thermal design—leading to cost reductions in mass production.


  • Diagram 1: Film capacitor for motor drive units
    Diagram 1:
    Film capacitor for motor drive units

  • Diagram 2: Vapor-deposited pattern
    Diagram 2:
    Vapor-deposited pattern

■Conductive polymer hybrid aluminum electrolytic capacitors for
 automobiles and industrial equipment

Electronic controls and miniaturization have advanced within the automotive and industrial equipment sectors recently, as have the performance and density of substrates on which aluminum electrolytic capacitors are mounted. As a result, Nichicon developed and launched the GYA series of conductive polymer hybrid aluminum electrolytic capacitors, which are compatible with high temperatures, long lifetimes and high ripple currents.
 The GYA series uses a hybrid electrolyte obtained by combining conductive polymer and electrolytic solution. This combination of proprietary propylene polymer formation technologies and the compatible electrolyte results in oxide film restoration performance and low ESR.
 The product dimensions are φ 6.3 × 5.8 L to φ 10 × 10 L, the rated voltage range is 25 V to 63 V, and the capacitance range is 10 to 330 μF, guaranteed for 4,000 hours at 125°C.
 We believe the applications for conductive polymer hybrid aluminum electrolytic capacitors will increase as the market continues to expand. With that in mind, we will accelerate the development of these capacitors and expand our lineup to better respond to demands such as higher capacity, higher heat resistance and higher withstand voltage.

Diagram 3: GYA Series of Conductive Polymer Hybrid Aluminum Electrolytic Capacitors

Diagram 3:
GYA Series of Conductive Polymer Hybrid Aluminum Electrolytic Capacitors

■Expanded ratings in the UCH series chip type aluminum electrolytic
 capacitors for automotive-related equipment

Equipment performance has improved in the automotive sector, since electronic circuits are frequently positioned in or near engine compartments to provide passengers with more space and comfort. These changes also signal a demand for components able to withstand high temperatures.
 To that end, we’ve launched the UCZ series with low-temperature ESR after durability testing, achieving further miniaturization and lower ESR than the UCH series.
 Product features include a 75 percent reduction in ESR variation after 2,000 hours compared to conventional products by adopting a low-transpiration, low-resistance electrolyte, and optimizing internal specifications to φ 6.3 × 7.7 L.
 In addition to product dimensions of φ6.3×7.7L, we added the sizes φ8×10L and φ10×10L.
The rated voltage range is 35 V, and the capacitance range is 47 to 330 μF.
 We plan to keep pace with the market in terms of product miniaturization, high capacity and high performance in line with high-density packaging.

Diagram 4: UCH Series Chip Type Aluminum Electrolytic Capacitors

Diagram 4: UCH Series Chip Type Aluminum Electrolytic Capacitors

■Snap-in terminal type aluminum capacitors for EV and PHV quick charge
 devices and onboard chargers

In line with the spread of electric vehicles (EV), infrastructure development is also advancing, with EV and PHV quick charge devices (hereafter referred to as “quick chargers”) being installed at expressway parking areas, roadside stations and even in government buildings. Quick chargers utilize snap-in terminal type aluminum capacitors, which typically have a voltage rating of 450 V and tend to be preferred in relatively small sizes and low prices. For this type of application, Nichicon’s LGG series (guaranteed for 2,000 hours at 105°C) is an excellent choice. If an even smaller product is required, we recommend the LGM series (guaranteed for 2,000 hours at 105°C), a 105°C ultra-miniature type product. In addition to a newly developed high capacity electrode foil, the LGM series employs durable electrolyte and electrolytic paper to produce the smallest class product size in the industry. This aluminum electrolytic capacitor is optimal for circuit designs aiming to save space.

Diagram 5: LGM Series of Snap-in Terminal Type Aluminum Capacitors

Diagram 5: LGM Series of Snap-in Terminal Type Aluminum Capacitors

Snap-in terminal type aluminum capacitors are also used in EV onboard chargers. Automotive applications require higher performance for general household appliances and industrial equipment. Thus, these capacitors are often selected for their reliability and long life, as they must perform in severe temperature environments and maintain high durability. Based on the long-life LGX series (guaranteed for 5,000 hours at 105°C), terminals with improved vibration-proof properties are used in environments where vibration conditions are severe. When insulation performance is required, an exterior sleeve is used to provide excellent withstand voltage performance, offering an optimal design.

By focusing on the automotive market, our company aims to further contribute to society by refining technological capabilities that enable us to meet future demands.

 
 
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