Performance analysis of a modified Current Source Inverter for photovoltaic microinverter applications

Operation and modulation of H7 current source inverter with hybrid SiC and Si semiconductor switches

“…3(b). It was originally proposed for a grid-tied PV system in [6]. Obviously, the large inductor is still in series with the DC source.…”

“…The seventh switch locates between the DC rails independently to lower down the conduction loss during null state intervals. Besides, Ref [6] has mentioned the lightly damped resonant behavior caused by the CL-type output filter and the overlap time compensation. In specific, every active state vector was separated by a null state vector, which was operated by the introduced switch S 7 alone.…”

“…In specific, every active state vector was separated by a null state vector, which was operated by the introduced switch S 7 alone. However, the modulation method with this topology proposed in [6] was expanded inadequately. Although the seventh switch was employed to reduce the conduction loss, the whole switching counts along with the switching dissipation were unfortunately increased as the commutating operation of the rear-end CSI circuitry was leaving unchanged.…”

“…The pulse-width modulation strategy proposed in [6] only focused on the overlap time compensation and glitch elimination during commutation sextants. The study on the modulation for the new H7 CSI topology was not further expanded.…”

“…To increase the operational range, references [5] designed H7 circuitries with current buck-boost operation capability. In addition, to reduce the conduction loss, reference [6] proposed a H7 circuitry with an additional shunt-connected switch for micro inverter application, where the seventh switch was utilized to substitute the null states in CSI commutations simply leaving the commutation of rear-end CSI circuitry unchanged and hence unfortunately the whole switching counts increase one third. This paper proposes a hybrid solution by using one silicon carbide (SiC) switch to replace the shuntconnected seventh switch and a novel modulation method to reduce the switching counts and losses of rear-end CSI circuitry.…”