Q. Methods for speed and torque control of induction motors?
The following are methods available for speed and torque control of induction motors.
• Pole-changing method
• Variable-frequency method
• Variable-line-voltage method
• Variable-rotor-resistance method
• Rotor-slip frequency control
• Rotor-slip energy recovery method
• Control by auxiliary devices (Kramer control, Scherbius control, Schrage motor)
• Solid-state control (variable-terminal-voltage control, variable-frequency control, rotor-resistance control forwound-rotormotors, injecting voltage into rotor circuit ofwound-rotor motors) usually discussed under power-semiconductor controlled drives.