Four quadrant 250 kW switchmode power supply for Fermilab Main Injector

A +/-700 volt, +/-350 amp switchmode power supply has been developed for the Fermilab Main Injector Sextupole Correction System. The four quadrant operation is accomplished by using four IGBTs in an H-bridge configuration with a switching frequency of 10 KHz. A current regulation bandwidth of 300 Hz is achieved with stability better than 250 ppm of rated current by using a high precision current transducer. The H-bridge outputs are filtered resulting in a maximum output voltage ripple of 2.5 volts peak to peak. The power supply has a power conversion efficiency better than 80% and works at near unity power factor throughout its operation. The critical considerations involved in this power supply are low inductance bus plate and snubber design, selection and thermal management of IGBTs, IGBT gate drive, PWM output filtering, and fiber optic controls. The paper will discuss the design and performance of the power supply.