Murata capacitor used in hybrid scooter

Four Murata Power Mono capacitors are utilised in the scooter's power conversion system, on a board designed for smoothing the inverter.

The capacitors are used to reduce the surge generated by the IGBT (insulated gate bipolar transistor).

Until now, film or aluminium electrolytic capacitors were used in this application.

However, these types suffer from low heat resistance as they both contain organic material.

Murata's ceramic capacitors are made entirely from inorganic materials and have an intrinsic resistance to high temperatures.

The capacitors used in the hybrid electric scooter application can be used in the standard automotive temperature range, up to 125C.

The Power Mono capacitors measure 32 x 40 x 4mm.

The next largest footprint in Murata's range is 5.7 x 5mm, so with a footprint around 87-times larger, the Power Mono capacitors are considered to be huge.

Despite their large size, they are helping to reduce the footprint of the scooter's inverter circuit as they are still smaller than their film and aluminium counterparts.

Murata's technology allows a capacitance per unit volume of 2.4uF/cm3, compared to 1.2uF/cm3 for film capacitors and 1.89uF/cm3 for aluminium electrolytic types.

Power Mono capacitors have an allowable ripple current of 1.56A/cm3.

Their capacitance is 52uF, effectively 38uF at 150V DC, with rated voltage of 200V DC.

Murata has designed metal terminals for the Power Mono that prevent cracks forming in the capacitor.

These gull-wing shaped metal terminals absorb any expansion, contraction or deflection of the PCB, while allowing the part to be reflow soldered.