sentences:  However, with the advent of microcontroller technology, the majority of advanced systems now feature digital control.The voltage-fed inverter features a filter capacitor on the input to the inverter and a series resonant output circuits.The voltage-fed system is extremely popular and can be used with either SCRs up to frequencies of 10 kHz, IGBTs to 100 kHz and MOSFETs up to 3 MHz.