Power factor correction (PFC) is a technique used in power electronics to improve the power factor of an electrical system. The power factor is a measure of how effectively electrical power is being utilized by a load. It is the ratio of real power (active power) to apparent power in an AC circuit and is expressed as a value between 0 and 1.
A power factor of 1 (or 100%) is ideal, indicating that all the electrical power is being effectively used to perform useful work. However, in many practical applications, the power factor is less than 1 due to the presence of reactive components (inductance and capacitance) in the load.
When the power factor is less than 1, it means that a portion of the supplied electrical power is not being utilized efficiently. Reactive power, represented by the imaginary component of the apparent power, circulates between the load and the source without performing any useful work. This leads to increased current flow in the system, which can result in higher losses, reduced efficiency, and increased stress on power distribution systems.
Power factor correction is employed to mitigate these issues and optimize the power utilization. This is typically achieved by adding power factor correction circuitry to the load or power supply. There are two main types of power factor correction:
Active Power Factor Correction (Active PFC): Active PFC uses power electronics components, such as boost converters or buck-boost converters, to actively control the input current drawn by the load. The converter adjusts the input current waveform to be in phase with the voltage waveform, effectively reducing the reactive power component and improving the power factor closer to 1.
Passive Power Factor Correction (Passive PFC): Passive PFC uses passive components like capacitors and inductors to compensate for the reactive power in the system. These components are added in parallel or series to the load and are designed to create an opposing reactive power effect, canceling out some or all of the reactive power in the load and thus improving the power factor.
Power factor correction is essential in various applications, especially in industrial settings where large loads are involved. It helps to reduce energy waste, improve the efficiency of power distribution, and comply with utility regulations and standards. By achieving a higher power factor, power systems can operate more economically and reliably.