We have analyzed this. Currently the implementation is, allotted chart rendering space is same for whole doughnut and semi doughnut. So on rendering the semi doughnut, more free space is left around the chart. This is because the center point to draw the doughnut and semi doughnut is same now. So we have logged an feature request for this “To Position the doughnut series in chart based on its size”. A support incident to track the status of this feature has been created under your account. Please log on to our support website to check for further updates
Please let us know if you have any concern.