This chapter gives comprehensive coverage of induction motor drives, including different drive configurations, control topologies, estimation of signals, and speed sensorless control. The technology has gone through a dynamic evolution in the last two and half decades and is currently advancing with large momentum for the future. The literature in this area is very rich. Voltage-fed converter drives are most commonly used in industry in a wide power range that covers a few watts to multi-megawatts, although current-fed converter and cycloconverter drives are also used mainly in the high-power range. Cage-type machines are most common because of their simplicity, ruggedness, and cost effectiveness, but occasionally wound-rotor machines are also used in the high-power range with slip power recovery control. Doubly fed machines are expensive and have the disadvantages of slip rings and brushes. Static Kramer and static Scherbius drives have been used in industry for limited range speed control near the synchronous speed. Their converter costs are somewhat cheaper than that with cage machines, but the additional disadvantages are lagging line power factor, harmonic distortion of line current, nonreversible speed control, the need for separate starting, and, of course, a 60-Hz line transformer in the path of slip power flow. Scherbius drives with a cycloconverter and two-sided PWM converter system can solve some of these problems. A special application of a Scherbius drive was mentioned for a 400-MW hydroelectric power plant variable-speed generator/pump storage system. Overall, slip power recovery drives will tend to become obsolete except in very special...