What are aluminum electrolytic capacitors used for? What is the shelf life of aluminum electrolytic?

With the continuous development of electronic technology, the application scenarios of capacitors are also evolving. Capacitance will continue to increase, while the size will become smaller. High-frequency performance and stability in high-temperature environments will be the focus of capacitor research.

 

What are the uses of aluminum electrolytic capacitors?

Aluminum electrolytic capacitors are large, high-power solid-state capacitors. They use aluminum oxide film as the dielectric and aluminum foils as the electrodes at both ends. This type of capacitor features high capacitance, high voltage, and low ESR (Equivalent Series Resistance), making it widely used in high-power applications such as power supply filtering, DC coupling, and inverters.

 

As we all know, solar energy, as a new energy source, can provide clean and pollution-free energy for our lives. Curious users might wonder: What is the connection between new energy and aluminum electrolytic capacitors? Because the current generated by photovoltaic power generation systems is direct current (DC), while civilian electricity is mainly supplied by alternating current (AC), and solar power generation will ultimately be grid-connected, this means that solar power generation must use inverters to convert DC electricity into AC electricity to drive household appliances and other loads.

 

Therefore, inverters play a crucial role in solar power generation systems. The main function of the inverter is to convert the variable DC voltage of the power source into undisturbed AC sine wave output, which can be used by devices or fed back to the grid. Now let's specifically discuss the applications of aluminum electrolytic capacitors in the field of new energy.

 

1. Key to improving the lifespan of photovoltaic inverters

The reliability of each component determines the lifespan of photovoltaic inverters. Although semiconductor components typically achieve this level of reliability, it can be a challenge for passive components, especially electrolytic capacitors. Enhancing the reliability of electrolytic capacitors has become one of the keys to improving the reliability of photovoltaic inverters.

 

2. Role of electrolytic capacitors in photovoltaic inverters

Photovoltaic inverters can be seen as inverters for special applications powered by DC power sources, with an output frequency of 50Hz or synchronized with the grid's 50Hz. There are no current pulses generated by rectifier circuits of rectifiers. Therefore, the function of the aluminum electrolytic capacitors on the DC bus is to act as DC bus capacitors or "DC-Link" capacitors, absorbing the extremely high-frequency harmonic currents generated by the inverter, as well as three times the output frequency and high-frequency harmonic currents.

 

What is the Shelf Life of Aluminum Electrolytic Capacitors?

The shelf life of capacitors refers to two aspects: the storage time and the duration of use. The industry may not be able to provide a definitive answer regarding the storage time, but the duration of use is generally well understood. Few people who use capacitors would inquire about the shelf life, but rather they might ask about the lifespan or how long a capacitor can be used. However, this article will analyze the shelf life of capacitors.

 

I. Duration of Use of Capacitors

There is no specific term for the duration of use of capacitors within the capacitor industry. Generally, people directly inquire about the lifespan of capacitors, which refers to the duration of their use rather than the shelf life.

 

① The lifespan of common capacitors such as aluminum electrolytic capacitors is quite evident. The electrolyte inside aluminum electrolytic capacitors depletes with each use. The lifespan of capacitors like these can reach 3-5 years, even for high-end products. If an aluminum electrolytic capacitor can last for 10 years, it is extremely rare.

 

② Capacitors like ceramic capacitors have a very long lifespan, starting from around 10 years. However, the lifespan of such capacitors depends on their quality. If they are subjected to breakdown, they will be damaged.

 

③ The lifespan of capacitors like metal film capacitors depends entirely on the raw materials used. Capacitors produced from ordinary raw materials may become ineffective after 2-3 years, while those made from better materials can have a lifespan of up to 10 years.

 

2. Shelf Life of Capacitors

How many years can electrolytic capacitors be stored?

To answer this question, we need to know which parameters and performance of electrolytic capacitors are affected by prolonged storage. In general, the parameters of electrolytic capacitors mainly include capacitance, voltage, DF (Dissipation Factor) angle, ESR (Equivalent Series Resistance), leakage current, etc. Through experimental testing, we have found that the parameter of electrolytic capacitors affected by prolonged storage is the leakage current, which increases with longer storage time.

 

This is why some electronic shops dare to stock up on capacitors for sale. So, how should we store capacitors?

① The first consideration is the warehouse environment. It is not advisable to store capacitors in excessively humid conditions, as even a few days in such conditions can affect the capacitance and withstand voltage of the capacitors.

 

② Overly dry environments should also be avoided because the materials inside the capacitors are flammable. High temperatures in dry environments may lead to spontaneous combustion.

 

③ It is essential to prevent capacitors from coming into contact with air during storage. Capacitors without packaging bags are particularly vulnerable to oxidation and corrosion from exposure to air, which directly affects their lifespan.

With the continuous development of electronic technology, the application scenarios of capacitors are also evolving. Capacitance will continue to increase, while the size will become smaller. High-frequency performance and stability in high-temperature environments will be the focus of capacitor research.

 

Long lifespan and price optimization of capacitors will also be the direction of future capacitor development. For electronic engineers, understanding the characteristics and application scenarios of capacitors, as well as mastering the methods and techniques for selecting suitable capacitors, is essential.