Standard solutions used in power applications to convert DC waveforms to AC waveforms are known as inverters. These products are used in Uninterruptable Power Supplies (UPS); in frequency converters that convert the alternating current (AC) in direct current (DC), to modulate it afterwards in a variable frequency; in inverters used to generate alternating current from direct current sources, supplied by batteries or renewable energies sources, like eolic turbines or solar panels.


    Up to now, all improvements in high energy storage chokes and output ripple filtering were more focused on cost reduction than on size or thermal performance improvements. Therefore all improvements until now are based on silicon steel cores, used for high current levels, but with high losses. Later, it was launched a ferrite solution for currents up to 40, 50 and 60, with Pot Core format. Its limitation was due high size needed in sinteritzation before curing, process with temperature higher than 1000 degrees.


    Premo have developed Multi-E 65, 71 and 80 serie for these applications, used for currents from 40 to 50A and with a high efficiency, but the new AIC series achieves solutions for powers from 2500W up to 100KW depending on the model.
 

    AIC series advantages are its small sizes, from 320 mm wide and 270 mm high as maximum. That makes it more compact, it is 12% smaller than other similar competitor components. This series meets the applications needs with half of the current size. This is achieved by a high power density and high flux density in the core achieving 10% higher efficiency compared to similar solutions in the market. At the same time is able to work at ripple frequencies up to 25kHz. As well as these advantages, AIC serie has a low cost.

Key points:

• High efficiency (>99%) due to very low losses design
• Very good inductance stability vs. temperature
• High storage currents (up to 150 A)
• High current density
• Single phase and 3-phase formats
• Lower size in comparison with other technologies
• Operating temperature up to 25kHz
• Wide operating temperature range 

 

The AIC series is the first standarized solution presented in the market. Its technology is based on amorphous cores: The silicone iron assures permeability, linearity and high flux density capabilities, while the amorphous structure reduces the hysteresis loop losses in the core. This series covers inductances from 250uH up to 6mH; can be used for tri-phase and single-phase systems, and uses a simplified mechanical fixation to the inverter compared to similar competitor’s products. The mechanical fixation consists on an aluminum base for screws or rivets and terminal blocks to easily connect the component to the inverter. Its temperature and frequency losses are much stable and reduced: First ones are constant from -30ºC up to 120ºC allowing high operating temperatures without affecting component efficiency; the second ones are below 10W per kHz. These performances make this series suitable for the most critical and demanding applications in the market.

                                         Losses vs Temperature

 

                                            Core losses vs Frecuency

 

Due to these advantages, AIC series can improve inverters efficiency, critical parameter in renewable energies applications.

The following graph shows a comparison between AIC series efficiency and others market technologies, like ferrite or iron powder.
 

                                              Efficiency comparison.
                                           Based on a 25kVA inverter