Electric machine with permanent magnets and choke cage on the rotor capable for direct operation on electric network with high power factor

Abstract

The proposed electric machine combines permanent magnets (5), a choke cage (6) and an optimised rotor geometry to enable direct connection to the power grid without the need for additional reactive power compensation or the use of a voltage and frequency converter. Thanks to the Lq / Ld ratio greater than 2 and low THD (<5 %), and the induced voltage deviation of less than ±10 % compared to the mains voltage, a high power factor is achieved in the entire operating regime. The choke cage additionally increases the stability of operation on the network and improves the behavior during synchronisation and transients, as well as during load changes.The proposed electric machine combines permanent magnets (5), a choke cage (6) and an optimised rotor geometry to enable direct connection to the power grid without the need for additional reactive power compensation or the use of a voltage and frequency converter.Thanks to the Lq / Ld ratio greater than 2 and low THD (<5 %), and the induced voltage deviation of less than ±10 % compared to the grid voltage, a high-power factor is achieved in the entire operating regime. The choke cage further increases the stability of operation on the grid and improves the behaviour during synchronisation and transients, as well as during load changes.