PV educator

Thew following list of commercially available MI was tabulated in Table 1.





Reference :

Sher, H.A. and Addoweesh, K.E., 2012. Micro-inverters—Promising solutions in solar photovoltaics. Energy for Sustainable Development, 16(4), pp.389-400.

The flyback inverter secondary winding acts as an unfolding stage in a grid connected scnario. The switches associated with them needs gate driver circuits. The question here is that can we consider them as a half bridge circuit so that it is possible to use a half bridge driver ic with it. To answer this consider the Fig. 1 that depicts two different types of unfolding configurations. The working although is same lets consider the one with no center tapping.

Problem 

While simulating a grid connected PV system using co-simulation among PSIM and SIMULINK i was getting error. The error stated that

Algebraic state in algebraic loop containing 'SCMPPT_sensorless_v4_buckboost_ok/Product3' computed at time 0.0005 is Inf or NaN. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances).

Reading research papers is must for carrying out updated research that too in right direction. When I was stuck for almost two months on the design issues related to grid-connected PV systems I worked hard to get my issues resolved. While reading and reading and reading I read thesis reports, research papers and a lot of online articles. However, the following papers helped me a lot in expanding the breadth of my knowledge base.

Problem

I encountered a strange problem while co-simulation of a PV grid connected inverter. The problem was that for simulation time less than 2 sec, the simulation results were ok. For time more than 2.5 sec the results were bad. See these figures.

Flyback inverter is a device that converters the DC into AC with the use of flyback transformer. For this inverter topology no dc-dc converter is required as the dc voltage is not related to the operation.  It is simple, has less component count hence reduced cost and has advantage of isolation through transformer[4]. Let's see how it works.

The question is what scheme of conduction to be used for PV grid tied flyback inverter. Either the Discontinous Conduction Mode (DCM) or the Boundary Conduction Mode (BCM). So here is the literature review for this question.

Difference between BCM and DCM

The difference between DCM and BCM is shown in the figure above. Now that it is clear that DCM has dead bands in it while BCM operates at the boundary of CCM lets have evaluation of these conduction modes.