Synchronous motor drives-a forgotten option

Before the evolution of the modern insulated gate bipolar transistor in the 1980s, thyristor fed synchronous motor drives were widely used and accepted as a reliable means to obtain variable speed operation of a mechanical load at good efficiency. However, since the turn of the century, permanent magnet motor drives have assumed favor as the drive of choice for high efficiency, high performance applications such as traction and synchronous motor drives have disappeared from all but the very highest horsepower applications. This paper discusses the features of a modern synchronous motor drive which suggests that this type of drive could compete favorably with a PM motor drive. An example analysis utilizing the characteristics of the 2007 Camry hybrid car is used as an example.