3 Control of synchronous machines

Fernando Briz and Gonzalo Abad

3.1 Introduction

Synchronous AC machines are a type of machine in which, in steady‐state conditions, the rotor speed in electrical units is equal to the frequency of the stator current. Generally speaking, synchronous machines provide higher performance compared to induction motors, but at an increased cost and reduced robustness, mainly owing to a more elaborate rotor construction. Synchronous machines have been used for decades and have played a major role in high‐power applications. However, it has been during the last two decades, with the introduction of rare‐earths magnet materials, that the permanent magnet synchronous machines (PMSMs) have emerged as a key element for the development of high‐performance electric drives. PMSMs are excellent candidates for applications requiring high torque and power densities, as well as high efficiency. They can be found in multiple sectors, with powers ranging from fractional horsepower up to the MW, and in multiple applications including hybrid and electric vehicles, trains, large wind‐turbines, servo‐drives, and household appliances. Owing to this, although other types of synchronous machines will also be covered, this chapter is mainly devoted to the PMSM. Thus this chapter presents a similar structure to the previous chapter. First of all, the model of the machine is analyzed; based on these models, vector control is addressed. After that, sensorless control ...

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