Single-phase controlled rectifiers

This chapter focuses on single-phase controlled rectifiers that are used in a wide range of applications. Line-commutated rectifiers with diodes, covered in a previous chapter of this handbook, do not allow the control of power being converted from ac to dc. The main disadvantages of the classical line-commutated rectifiers are that they produce a lagging displacement factor with respect to the voltage of the utility, and they generate an important amount of input current harmonics. The standard can be satisfied only by adding huge passive filters, which increases the size, weight, and cost of the rectifier. This standard has been the motivation for the development of active methods to improve the quality of the input current and, consequently, the power factor. An important issue in power electronics is the power losses in power semiconductors. The conduction losses are produced by the current through the semiconductor juncture, so these losses are unavoidable. The single-phase boost rectifier has become the most popular topology for power factor correction (PFC) in general purpose power supplies.