ModCap – the new modular capacitor concept

ModCap has been designed to minimize the stray inductance; values below 14 nH are achieved for the whole series. Thanks to its design, the capacitors can be fitted very near to the IGBT modules, thus producing very short lead lengths. This stops any substantial voltage overshoot at the IGBT modules when the current is shut off. As a result, generally, no snubber capacitors are needed.

ModCap is based on long experience designing resin filled capacitors. The unique metallization of the films maximizes self-healing capability while withstanding high current densities, thus reducing losses. The capacitor dimensions have been designed for current and future IGBT power modules to optimize the DC link unit's space requirements in terms of dimensions and power.

The main advantages of a modular capacitor are reduced volume, low cost, standard design, low stray inductance and high current and energy density. Additionally, ModCap enables the plug-and-play philosophy through its special mechanical design, matched to existing SiC/IGBT power modules.

As a standardized product, the ModCap is compliant with most of the industry standards: EN 45545-2, IEC 61071, IEC61881-1, UL, and others. Since the moment of purchasing, our customers receive a fully validated product with all the necessary documentation.

Despite of being a standard design, TDK is also able to offer customized solutions. Thanks to our broad catalog and technical support, SPICE models and electromagnetic and thermal FEA simulations; TDK delivers excellent solutions for customer-specific requirements.

Up to 90 ºC of hot-spot temperature can be achieved during operation thanks to the use of high crystallinity BOPP and our fine-tuned automated process parameters. Furthermore, considerably enhanced self-healing properties are achieved.

For precise heat distribution in the capacitor, TDK also offers FEA simulations tailored to your specific electrical and mechanical conditions. TDK can simulate ModCap in customer setup, taking into account the electrical conditions and all other aspects that may have an influence, such as external electromagnetic interference, the cooling system, the mechanical assembly, etc.

All materials used in rail vehicles for passenger transport must meet the EN45545-2 standard in order to achieve the highest level of safety possible in the event of a fire. Railway vehicles are classified in accordance with the fire hazard level associated with their design and operation.

The three hazard levels are: HL1, HL2 and HL3 with HL1 being the lowest requirement and HL3 being the highest. ModCapTM/ New modular Standard Series meet the high requirements of the new European fire protection standard EN45545-2, reaching safety levels up to HL3 in the requirement set applicable to power capacitors (R22, R23 and/or R24).

Therefore, ModCap can even be installed in bunks and bed wagons that cross long tunnels and railway vehicles operating on the underground tracks.

The basis for the use with high harmonics is the internal mechanical construction of the ModCap, i.e., the even distribution of the flat windings used and their short lead lengths. Also, by using special FAE software, external and self-induced electromagnetic fields can be detected, and appropriate countermeasures can be taken. TDK also supports its customers in designing the mechanical interface to the capacitor.