Electronics

Current Limit Control is one of the output voltage control strategy of chopper. In this method, the ON and OFF time of chopper circuit is governed by the previously set value of load current. This technique is different form Time Ratio Control method.  In this technique, the chopper is switched ON when the load current … Read more

There are mainly two techniques or methods to control the output voltage of a chopper: Time Ratio Control Method and Current Limit Control. The output voltage of chopper depends on the duty cycle. By changing the duty cycle, the output voltage can be varied. Both the methods, employ some technique to vary the duty cycle. … Read more

What is a Chopper? A chopper is a static device that converts fixed DC input voltage to a variable DC output voltage. It is basically a high speed ON/OFF semiconductor switch. It may be thought of as DC equivalent of an AC transformer since they behave in an identical manner. Chopper is fed through a … Read more

A single phase half wave controlled rectifier is a thryristor based circuit which produces output voltage for positive half of the supply voltage. However, the phase relationship between the initiation of load current and supply voltage can be controlled by changing firing angle. This is the reason; it is called phase controlled half wave rectifier. … Read more

Single Phase Half Wave Controlled Rectifier, as the name suggests, is a rectifier circuit which converts AC input into DC output only for positive half cycle of the AC input supply. The word “controlled” means that, we can change the starting point of load current by controlling the firing angle of SCR. These words might … Read more

Definition: Phase Control of SCR means having control on the phase relationship between the start of current through the SCR and source voltage. Phase Control of SCR Explanation: Whenever we talk of phase angle, we generally mean the angle of a sinusoidal quantity at any instant of time. Phase control of SCR means the phase … Read more

Firing Angle of SCR is defined as the angle between the instant SCR would conduct if it were a diode and the instant it is triggered. We know that, there are two conditions which must be satisfied for turn on of an SCR. They are: SCR must be forward biased i.e. its anode voltage must … Read more

Natural or Line commutation is a Class-F SCR commutation technique in which, a thyristor is turned off due to natural current zero and voltage reversal after every half cycle. This commutation method is only applicable for AC circuit and mostly used in Phase-Controlled Converters, Line-Commutated Inverters, AC voltage controllers and Step-down cycloconverters.  Principle of Class-F … Read more

Class-E Commutation is one of the forced commutation method to turn off an SCR / Thyristor. An external current pulse is used in this technique to commutate SCR. This is the reason, Class-E commutation is also known as External Pulse Commutation. This external current pulse is obtained form a separate voltage source. . Condition for … Read more

Class-D Commutation is a commutation method used to turn off thyristor in a DC circuit by the application of a sudden reverse voltage across the terminals of SCR. This is the reason, it is also called Impulse Commutation. A Class-D commutation circuit consists of Main Thyristor T1, Auxiliary Thyristor TA, Capacitor C, Diode D and … Read more