Uncontrolled Generator Fault Protection Of Novel Hybrid-excited Doubly Salient Synchronous Machines With Field Excitation Current Control

Uncontrolled Generator Fault Protection of Novel Hybrid-excited Permanent Magnet Machines Utilizing Field Excitation Current Control.

Abstract:   

In this paper, the fault protection capability of a novel hybrid-excited permanent magnet (PM) machine is examined to illustrate its great capability to prevent the dangerous overvoltage issue from the uncontrolled generator fault (UCGF) at high speed operation. PM flux of the novel hybrid-excited PM machine is inherently short-circuited when the field excitation current is not fed into the excitation windings. Therefore, when the machine UCGF is detected in the high speed region, the DC-link overvoltage issue can be effectively reduced by forcing the field excitation current to zero. Since only the field excitation current is utilized to protect the machine and inverter switches from the UCGF, it is simple to implement and the concept of proposed control strategy can also be applied to other hybrid-excited PM machines.