friquency converter

Normally rotary type frequency converters are used for Medium Frequency up to 10 K HZ. Mechanically coupled Motor generator sets are used .The common power supply normally available is 420 to 440Volts 50 cycles / 60 cycles supply.The prime mover of generator is a 3 phase induction Motor suitable to operate with available power supply . The mechanically coupled generator generate the required voltage and frequency.The max. speed attainable for Induction motor with 50 cycle supply is 3000 RPM .{N = 120 f / P (120 x 50 / 2 ) = 3000 RPM } Minimum number of poles being 2

For the Generator to generate 8000 cycles ( 8 K HZ ) the number of poles required

P = 120 f / N 120 x 8000 / 3000 = 320 Poles.

The design problem is how to accommodate so many number of poles in the stator field winding . For this field winding is also wound on the stator and rotor is designed with as many number of Teeth as required Poles . This Design has made it simple for manufacturing.The out put from the Main winding will be required frequency and voltage as per design .