Some definitions

,

where ω- cyclic frequency, t- current time.

2). The angle, at which an uncontrolled rectifier is turned on, names as a point of natural turning on.

The angle when controlled rectifier is turned on just as a control pulse is applied names as a control angle (turning on, regulating, ignition angle). This angle is fixed concerning a point of natural turning on.

3). The average value, or direct component of a current (voltage) is a square between a current (voltage) waveform and abscissa axis averaged during of waveform period.

Figure 1.2

4). The root mean square value of periodical current is same value of a direct current, which flowing during of waveform period through the given part of a circuit, produces as amount of heat as considered alternating current.

Amount of heats is produced by the direct current is

Q₌=I²_RMS ּּ R ּ T;

Amount of heat is produced by the alternating current is

But the condition Q₌ = Q _~ must be executed.

From here

As U=IR, so

5). Let's suppose that the uncontrolled rectifier is a special case of controlled rectifier at

ά = 0.

6). Let’s consider thyristor as logical switch.