Method for connecting an electric asynchronous machine of a powertrain to an electric grid

Method for connecting an electrical three-phase machine as a drive machine of a drive train to an electrical grid,

• wherein the drive train has a drive shaft of a driven machine, the drive machine, a differential drive, and a differential transmission with three drives or outputs,
• of which one output is connected to the drive shaft, a first drive to the drive machine, and a second drive to the differential drive,
• wherein the drive machine is started up in a first phase from an rpm of zero or approximately zero, while a drive is connected simultaneously to the other drive or to the output, and the drive machine is separated in this phase from the grid,
• wherein in a second phase, the drive machine is connected to the grid, and the connection between one drive and the other drive or the output is separated,
• and wherein the rpm of at least one drive and/or output is determined,
• wherein
• the grid frequency is detected in particular by measuring technology, or a grid frequency-fluctuation range is defined,
• wherein the drive machine is connected to the grid when the frequency produced from the rpm of the drive machine deviates by less than ±5.0% from the grid frequency,
• and wherein the connection between one drive and the other drive or the output is separated.