Tag: Power electronics
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AC to AC Power Converters with Intermediate DC Link: Types, Features & Applications
This category of AC drives that is often referred to as “Variable Frequency Inverters” is one of the most extensively used drives in industrial motor control applications. Generally, the concept of these inverter drives can be summarized into three parts: We have two main classifications of these AC drives that are based on the aforementioned…
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DC to DC Power Converters: Function, Types, Operation & Applications
DC to DC power converters also referred to as choppers provide the means to change one DC voltage to another. Normally the conversion is to a lower voltage however, we also have step-up converters. DC to DC power converters are fed from a DC supply usually comprising an uncontrolled AC to DC converter or alternatively…
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Single-Phase & Three-Phase Inverters: Function and Operation
What is the Purpose of Inverters? Whereas dc machines are controlled by varying the voltage and current, ac machines are often controlled by varying the voltage and frequency. One way of accomplishing this is by using inverters. The process of converting ac from dc is referred to as inversion. Some of the reasons why ac…
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Insulated Gate Bipolar Transistor (IGBT) – Structure, Operation & Applications
IGBT is a voltage controlled device. It has high input impedance like a MOSFET and low on-state conduction losses like a BJT. In other words, this power device combines the voltage control of the MOSFET gate with the superior conduction characteristics of the bipolar device. Nonetheless, the IGBT utilizes injected-charge modulation in the base region…
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Optothyristors: Features & Principle of Operation
Silicon Controlled Rectifiers (SCRs), Triacs and other solid-state devices used for switching larger voltages and currents ON and OFF are referred to as thyristors. Thyristors control switching in an ON-OFF way, in the same way to a light switch which is different from a transistor that can vary the amount of current in its emitter-collector…
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The Shockley Diode Features & Operation
The Shockey diode is a four layer sandwich of PNPN semiconductor material very similar to the SCR but without a gate as illustrated in the Figure 1.0 below: The Operation of Shockley Diode A Shockley diode can be turned ON by applying enough voltage between anode and cathode. This voltage will cause one of the…
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The Diac Features & Applications
Features of a Diac The diac is a two-terminal, semiconductor, bi-directional switching device. It can conduct in both directions. The diac closely resembles a PNP transistor without an external base terminal. Operation of a Diac The diac does not conduct except for a small leakage current) until the breakover voltage VS is reached, typically 20…
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Basic Features of Power Semiconductor Controlled Drives
Power electronics deals with the applications of solid state electronics for the control and conversion of electric power. The conversion systems require switching power semiconductor devices on and off. The key components of an electric drive controlled by a power semiconductor converter are illustrated in the figure below: The converter regulates the flow of power…
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Switchgear Equipment
Switchgear can be defined as equipment used for controlling, regulating and switching ON and OFF power circuits. Switchgear units range from the small moulded-case unit circuit breakers in a household panel board to the huge, air break switches on 750 kV transmission lines. Switchgear equipment is generally divided into four groups, namely: Disconnect/Isolator Switches Disconnect…