The analog control systems were a unique way for implementation in AC drives control for many years. The implementation of microprocessors in the AC drives control has begun in the speed and position loops. The slow speed (position) change allows implementation of 8 or 16 bit microprocessors. The fast development of microprocessors enables realization of control strategies and causes the analog control systems to be completely replaced with digital systems. The microprocessor used in AC drives must be able to do a lot of mathematics in minimal processor cycles. The DSPs are specialized microprocessors with the specific architecture, which allows that. Some AC drives using microcontrollers are discussed.