CYCLOCONVERTERS
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In industrial applications, two forms of electrical energy are used: direct current (dc) and
alternating current (ac). Usually constant voltage constant frequency single-phase or three-phase
ac is readily available. However, for different applications, different forms, magnitudes and/or
frequencies are required. There are four different conversions between dc and ac power sources.
These conversions are done by circuits called power converters. The converters are classified as:
1-rectifiers: from single-phase or three-phase ac to variable voltage dc
2-choppers: from dc to variable voltage dc
3-inverters: from dc to variable magnitude and variable frequency, single-phase or threephase
ac
4-cycloconverters: from single-phase or three-phase ac to variable magnitude and
variable frequency, single-phase or three-phase ac
The first three classes are explained in other articles. This article explains what cycloconverters
are, their types, how they operate and their applications.

1.Operation Principles:
The following sections will describe the operation principles of the cycloconverter starting from
the simplest one, single-phase to single-phase (1f-1f) cycloconverter.

1.1. Single-phase to Single-phase (1f-1f) Cycloconverter:
To understand the operation principles of cycloconverters, the single-phase to single-phase
cycloconverter (Fig. 2) should be studied first. This converter consists of back-to-back
connection of two full-wave rectifier circuits. Fig 3 shows the operating waveforms for this
converter with a resistive load.