In this paper, we analyze new trends in nonlinear analysis and control of induction motors. In particular, nonlinear mathematical models in machine variables as well as in an arbitrary reference frame are found in Cauchy's form, and the motion control problem is studied for induction motors from closed-loop perspectives. Voltage-frequency and vector control concepts are examined, novel bounded controllers are designed, and advantages and drawbacks are discussed. The conventional constant volts per hertz principle, known as V/f control, is widely used, and torque-speed characteristics can be shaped by controlling the magnitude of phase voltages and the frequency. However, voltage-frequency control has been mainly studied from open-loop perspectives. In this paper, an innovative control law is synthesized to attain the constant and variable voltage-frequency operations from closed-loop perspectives, and beneficial advantages of the control algorithm designed have been utilized and thoroughly examined. An innovative procedure is reported to design controllers to attain the vector control of induction motors. To validate the results, controllers are designed and tested. Numerical and experimental studies have been performed and documented. (C) 2001 Elsevier Science Ltd. All rights reserved.