A series-resonant DC/AC inverter for impedance-load drives

A dc/ac inverter without cycloconversion configured by a half-bridge series -resonant inversion (HB-SRI) is presented. The inverter is a series resonat or with two auxiliary switches in shunt with the resonant capacitor so as t o configure adaptively the output current suitable for impedance load. The output sinusoidal voltage is synthesized by a series of equal-amplitude qua sisinusoidal pulses (QSPs) and the corresponding current is formed by unequ al QSPs and adaptively phase-shifts to the impedance load. The presented HB -SRI is operated by frequency modulation with a constant-on time control. S ystem modeling and waveform syntheses for the output sinusoidal voltage and its current are clearly derived. A typical design example of a 500W HB-SRI inverter is examined to assess the system performance. The power efficienc y is over 90% when the inverter output is above 200W, The total harmonic di stortions (THDs) for various impedance loads are all within 6%.