Power Electronics

What is Gate Turn Off Thyristor (GTO)? A Gate Turn Off Thyristor (GTO) is a power semiconductor device which can be turned ON and OFF by applying gate current. It is basically a pn pn device which is tuned ON by applying positive gate current and turned off by negative gate current at its gate … Read more

The main difference between a step-up and step-down chopper is that average value of output voltage of former is greater than its input DC voltage whereas it is less than the DC input voltage for latter. This is the basic but major functional difference between the two. Step-down and step-up choppers are static devices which … Read more

Definition: Step-up chopper is a static device whose average output DC voltage is greater than its input DC voltage. It is different from the step-down chopper. In step-down chopper, the average value of output voltage stepped down i.e. it is less than its input voltage. Working Principle of Step-up Chopper: To understand the working principle, … Read more

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