4 Cost Optimization

System cost is an important consideration for a micro inverter or portable power station. This section gives some insights into how system cost is positively impacted by moving from a SiFET-based two stage converter to a GaN-based single stage converter. The amount of power switches can be reduced in a cycloconverter. The switches used on the DC side need to be rated 170V for push-pull and flyback converters, whereas on the cycloconverter they can be rated 100V for a single panel input. The operating frequency of this new cycloconverters is in the range between 300kHz and 600kHz. That means the magnetic design (transformer and inductors) is much smaller compared to two stage converters. 'Two stage' converters typically operate below 100kHz in order to keep switching losses in the SiFETs small. In addition, the EMI filter to the grid is much smaller for a cycloconverter compared to a full bridge AC/DC. This results in an overall cost reduction. Figure 4-1 illustrates a cost comparison. A push-pull converter is used as 100% reference for relative comparison.

Figure 4-1 Cost Comparison

Cost on power switches increases slightly, whereas the cost on magnetics goes down significantly. As a result, the overall solution cost is down by 12%.