Technical Library

New Technology Trends in Aluminum Electrolytic Capacitors
for Power Electronics

NICHICON CORPORATION

Power electronics is a growing field, and Nichicon is increasing technical capabilities and the reliability of our products to meet the demands for solar and wind power generation, electric vehicles (EVs), hybrid electric vehicles (HEVs), railway cars, and inverter applications in industrial equipment and home electronics. NICHICON has developed aluminum electrolytic capacitors and film capacitors for these technologies including custom products tailored to meet our customers’ needs.

Today, there is a growing importance being placed on the use of energy-efficient inverters in power electronic devices. The shift to inverters enables higher system efficiencies and energy savings, and the components used are becoming smaller and required to withstand higher voltages. Aluminum electrolytic capacitors used in inverter power supplies and other control circuits have growing requirements to be smaller, withstand higher voltages and offer longer life. Withstanding higher voltages are required in solar and wind power generation applications, as well as other renewable energy-related fields. Other applications like AC servomotors where sudden and repeated charging and discharging is present high reliability is of major importance.

NICHICON has developed products that can withstand higher voltages, are smaller in size and offer better charging and discharging performance for use in a variety of industrial equipment in the power electronics field. Products developed to meet these requirements include—the LAS series (Figure 1) and the LNG series (Figure 2). New series include: the LGM series (Figure 3) and the LNU series (Figure 4).

■LAS Series Snap-in Terminal Aluminum Electrolytic Capacitors
Aluminum electrolytic capacitors are frequently used on the primary-side as filtering/smoothing capacitors in switching power supplies. Depending on where the power supply is used abnormal voltages may be applied to capacitors. In these locations power conditions are less than optimal so the input voltage varies. The capacitors must be able to handle these abnormal voltages and fail safely instead of shorting or catching fire. To achieve higher levels of efficiency and conserve energy, the trend has been to shift systems to higher voltages and make them compatible with power supplies worldwide. Accordingly, demand is increasing for aluminum electrolytic capacitors with higher withstand voltages.

 The LAS series is ideal for equipment used in locations where power supplies are unstable and abnormal voltages are present. The LAS series is designed for increased safety by preventing shorts and fires in the event of DC overvoltage. The LAS series has snap-in terminal construction, an endurance life rating of 2,000 hours at 105°C and has a small size. The LAS has been expanded to rated voltages of 450V, which is highest in the industry.

 The characteristics of the 450V-rated LAS series parts include the use of high reliability electrolytic foil to increase withstand voltage performance. Increasing the withstand voltage requires the use of an electrolyte that suppresses self-discharge. A special electrolytic paper suitable for withstanding high voltages boosts the withstand voltage characteristics at the material level. To prevent overloading of internal elements due to the application of abnormal voltages, the capacitor uses a voltage-compatible structure, achieving abnormal voltage performance that is the highest in the industry.

 By increasing the rated voltage above standard capacitors, Nichicon created a capacitor that can handle abnormal voltages of up to 675V, 45V higher than conventional components. 450V capacitors allows use within worldwide power supplies covering a range of voltages. As a result, the LAS series can be used with higher power supply voltages and for filtering/smoothing power supplies in regions where power conditions are less than ideal. Accordingly, the LAS series can be used in a wide range of applications.

[Figure 1] LAS series snap-in terminal aluminum electrolytic capacitors

[Figure 1] LAS series snap-in terminal aluminum electrolytic capacitors

■LGN Series Snap-in Terminal Aluminum Electrolytic Capacitors
The LGN series are smaller snap-in terminal aluminum electrolytic capacitors 3000 hour endurance rating with rated voltage and 105°C that are mainly used in various types of industrial equipment, such as for high-voltage inverter circuits in power electronics.
 Industrial equipment is moving toward higher system voltages to increase efficiency and conserve energy. Accompanying this trend is a growing demand for aluminum electrolytic capacitors that can withstand higher voltages in inverter power supplies and other control circuits. These requirements are particularly important in the renewable energy sector, such as solar and wind power generation. Previously the LGN series was limited to a rated voltage of 500V. Nichicon has expanded the LGN series to 600V, making it the highest voltage rating in the industry. The LGN series is ideal for power electronic equipment where energy-efficiency is paramount.
 The 600V-rated LGN series component uses a high reliability electrolytic foil that ensures long-term stability along with an electrolyte with enhanced restoring capabilities at high voltages and high-withstand-voltage electrolytic paper. This combination of materials allows Nichicon to achieve the highest voltage level in the industry. For the LGN series Nichicon developed a new electrolyte whose composition has been optimized to allow for voltage increases of 20–30%, enabling the LGN series to reach withstand voltages of 600V at 105°C.
 To meet required system voltages, multiple aluminum electrolytic capacitors can be connected in series, reducing manpower requirements. For example, three 400V products can be connected in series to meet a 1200V requirement. This same requirement can be met by connecting just two of our newly developed 600V products in series, which saves space and allows for optimized circuit design.

[Figure 2] LGN series snap-in terminal aluminum electrolytic capacitors

[Figure 2] LGN series snap-in terminal aluminum electrolytic capacitors

■LGM Series Snap-in Terminal Aluminum Electrolytic Capacitors
The LGM series are ultraminiature snap-in terminal aluminum electrolytic capacitors with endurance life ratings of 2,000 hours and 105°C. The LGM series is designed for use in a variety of industrial equipment, such as inverter circuits for power electronics and switching power supply circuits.
 Industrial equipment is becoming smaller with power savings and decreased resource usage. To meet this growing demand the use of smaller on-board components is required. The new LGM series was designed to meet this demand. The LGM series is the industry’s smallest, even smaller than the LGL series which was the smallest in the industry.
 The LGM series uses a specially developed high-capacitance electrolytic foil and an electrolyte and electrolytic paper that offer superb durability. As a result the LGM series is up to 16% smaller (product dimensions) than our current LGL series. The LGM series is the optimal aluminum electrolytic capacitor for space-saving circuit designs.

Product size comparison
Product ratings LGM series LGL series Product
dimensions
450V–180μF φ25x25L φ25x30L -16%
450V–180μF φ22x30L φ22x35L -14%
450V–390μF φ30x35L φ30x40L -13%
450V–820μF φ35x45L φ35x50L -10%

[Figure 3] LGM series snap-in terminal aluminum electrolytic capacitors

[Figure 3] LGM series snap-in terminal aluminum electrolytic capacitors

■LNU Series Screw Terminal Aluminum Electrolytic Capacitors
The LNU series are smaller screw terminal aluminum electrolytic capacitors with high withstand voltages and endurance life ratings of 5000 hours at 105°C. Product highlights include the use of high-withstand-voltage electrolytic foil, an electrolyte with enhanced oxide restoring capacity at high voltages to provide better long-term stability and has a low-density while having a high withstand voltage, and an enhanced heat dissipation structure. Compared to the LNT series the LNU series achieves a higher withstand voltage (rated voltage: 525V) and offers longer life (guaranteed to 5,000 hours). At the same time, this series is around 20–30% smaller than other products with voltage rating of 500V, contributing to smaller and more lightweight equipment. The LNU series can be used in high-speed charging and discharging applications in industrial equipment where loads vary considerably. The LNU series is also ideal for use in applications like AC servo motors, which are characterized by rapid charging and discharging in short periods of time.
 By offering a higher rated voltage than standard products, the LNU series is well suited for use in filtering/smoothing power supplies in regions where poor power supply voltage conditions lead to input voltage variations. To meet higher system voltage requirements, multiple aluminum electrolytic capacitors can be connected in series for optimizing circuit design.

[Figure 2] LGN series snap-in terminal aluminum electrolytic capacitors

[Figure 4] LNU series screw terminal aluminum electrolytic capacitors

NICHICON offers an extensive lineup of aluminum electrolytic capacitors with a variety of characteristics to meet our customers’ requirements. NICHICON will develop new and custom products that meet the most demanding requirements.

 
 
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