INTRODUCTION TO POWER ELECTRONICS
The development of solid-state motor drive packages over the last 30 years has revolutionized the application of electric motors. Any power control problem can be solved using them. The solid-state drives allowed dc motors to run from ac power supplies or ac motors from dc power supplies. The frequency of ac power can be changed to any other frequency.
Furthermore, the reliability of solid-state drive systems has increased while their costs have decreased. The versatility of these solid-state controls and drives has provided many new applications for ac motors which were formerly covered by dc machines. The application of solid-state drives has also provided flexibility for dc motors.
The development and improvement of high-power solid-state devices have caused this major change.