Nowadays, there are more applications than brush excitation systems that belong to the AC excitation system. Brushless excitation system overcomes the main characteristics of DC excitation system, so that the entire excitation system has no sliding contact part, but the brushless excitation still needs an excitation machine, and there are certain problems in running detection and maintenance. Since the rotor loop is rotating and there is no lead output, the voltage and current of the rotor loop can not be directly measured. The insulation of the rotor winding and the operating conditions of the Silicon rectifier and the rapid fuse are not easily monitored. In addition, there is a problem of excitation noise in the unbrushed excitation system. Many small and medium capacity units previously installed by AC excitation use this system. Because it is based on rectifier rectifier, there are electric brushes, rectifier and other conversion contact components, and the operation maintenance is large, and the adjustment speed is slow and the accuracy is poor. This excitation method has been eliminated.
