I. Introduction
There is a growing demand for off-grid power converters for pumping/irrigation applications which can be powered from PV modules plus battery type of sources. These converters should also be versatile enough to power a host of other loads such as street lights and agrarian equipments like chillers, threshers, etc as specified in [1]. This demands the develop-ment of a power converter which should be efficient, compact, reliable and cost effective. The voltage source inverters traditionally used for induction motor driven pump loads use an electrolytic capacitor at its dc-link [2]. This helps in absorbing the switching harmonics generated by the load and source side converters and maintains a smooth and constant dc bus voltage. These DC bus electrolytic capacitors are prone to failures [3] and are bulky in size. Generally, the types of converters which employ a low value film capacitor or no electrolytic capacitor at the dc-link are referred to as dc-link electrolytic capacitor-less inverters or reduced dc-link capacitor inverters. These type of converters have been an area of research for quite some time now [4]–[11]. All of these dc-link electrolytic capacitor-less topologies have fluctuating dc-link voltage [8]–[11]. Following are some of the benefits of a dc-link electrolytic capacitor-less inverters over the traditional ones that use large electrolytic capacitors in the dc-link:
they are compact, light-weight and have high power density [12]
absence of electrolytic capacitors which are susceptible to variations in the operating temperature [13] increases the probability of a greater lifetime [14]–[15]
may not require additional pre-charging circuits to reduce the inrush current [15]