I have major doubt regarding the benefit of driving the turbine and compressor independently by MGU-H. Thoughts have been borrowed from official F1 website where the analysis of PU comparison between Mercedes and Renault are done as follows:
1. With MGU-H of Mercedes PU mounted in between turbine and compressor, do they have 2 shafts- one connected directly from the turbine to the compressor. And another one connected to all three elements ie turbine-mgu-h-compressor? That's what is implied from the statement :"Mercedes' solution offers the possibility of driving the two elements independently" , isn't it?
2. It's been mentioned in the article that in case of Mercedes, MGU-H only has to run the compressor.Thus minimizing extra power that needs to be spent to drive the turbine which is the case of Renault. But the question is (assuming my point no.1 to be correct), since all three elements are mounted on a common shaft. How can MGU-H run the compressor alone?
3. Negate my first point and let's assume that independence is attained by 2 shafts again-one connected to MGU-H from the turbine and second shaft between MGU-H & compressor. In this case, as compressor is solely being driven by MGU-H which harvests energy from exhaust exiting the turbine. Won't this lead to greater amount of turbo lag? As we can see there's a difference between compressor being driven directly by the turbine and compressor driven by MGU-H?