Power Electronics Tutorial
Power Semiconductor Devices
Phase Controlled Converters
DC to DC Converters
Inverters
AC to DC Converters
Power Electronics Resources
Selected Reading
- Linear Circuit Elements
- Power Electronics - Switching Devices
- Power Electronics - Introduction
- Power Electronics - Home
Power Semiconductor Devices
- Solved Example
- Power Electronics - MOSFET
- Power Electronics - IGBT
- Power Electronics - BJT
- Power Electronics - TRIAC
- Silicon Controlled Rectifier
Phase Controlled Converters
- Solved Example
- Power Electronics - Dual Converters
- Reactive Power Control of Converters
- Performance Parameters
- Effect of Source Inductance
- Power Electronics - Pulse Converters
DC to DC Converters
- DC Converters Solved Example
- Resonant Switching
- Power Electronics - Control Methods
- Power Electronics - Choppers
Inverters
AC to DC Converters
- Solved Example
- Power Electronics - Matrix Converters
- Integral Cycle Control
- Power Electronics - Cycloconverters
- Single Phase AC Voltage Controllers
Power Electronics Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
Integral Cycle Control
Power Electronics - Integral Cycle Control
Integral cycle controllers are converters with the abipty to perform direct switching without losses. The process directly converts AC to AC without having to perform the intermediate processes of AC to DC then DC to AC.
The basic integral control cycle is sinusoidal in nature. It operates by combining and epminating higher frequency half cycles from AC input. The controllers are normally, turned ON of OFF during half cycles where the voltage input is at zero since only the full or half cycles are utipzed. Therefore, integral cycle circuits achieve switching at zero voltage without requiring a resonant circuit.
The diagram below shows a simple integral cycle controller. It contains a load and a power switch, which performs the direct conversion. This diagram shows the conversion of source frequency from a factor of three to one.
Power Factor Control
Power factor control, also known as correction of power factor, is the process of reducing the amount of reactive power. The power electronic device used in this case is called a power factor controller (PFC). From the power triangle (which comprises reactive, true and apparent power), the reactive power is at right angle (90°) to the true power and is used to energize the magnetic field. Although reactive power does not have a real value in electronic equipment, the bill for electricity comprises real and reactive power costs. This makes it necessary to have power factor controllers in electronic devices.
Power factor (k) is defined as the ratio of the real power (in kW) to the reactive power (in kVAr). Its value ranges from 0 to 1. If a device has a power factor of 0.8 and above, it is said to be using power efficiently. Incorporating a PFC ensures the power factor ranges from 0.95 to 0.99. Power factor controllers are mainly in industrial equipment to minimize reactive power generated by fluorescent pghting and electric motors.
To ensure power factor is improved without causing harmonic distortion, the conventional capacitors should not be used. Instead, filters (combination of capacitors and reactors) for harmonic suppression are used. The figure below shows a harmonic filter.
The above type of harmonic filter is referred to as a single tuned filter. A quapty factor Q of this filter is defined as quapty factor of its reactance (XL) at Q (tuning frequency) where Q is given by (nXL/R).
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