What Is Active Power Factor Correction (PFC)?

Electrical devices and circuits aren’t 100% efficient—some electrical power input will always be lost, leading to lower output power. This ratio of “apparent” power (or input) to “real” power (output) is the power factor (PF).

The closer the power factor of a device or circuit is to 1:1, the more efficiently it performs. This criterion matters: the EU and other international organizations regulate the minimum PF and maximum level of harmonics a device can have before it can be sold in its respective markets. Electronics manufacturers also look at PF when procuring electronic devices to ensure they purchase the most efficient products.

What Is Active PFC?

Power factor correction (PFC) describes various methods that correct low power factors. For example, manufacturers can add reactive components that increase the total reactive power of a circuit. This corrects displacement and inefficiency to bring that ratio closer to 1:1.

In active PFC, a switching converter modulates the distorted wave and reshapes it into a sine wave. This creates harmonics in the new signal only at the switching frequency, which can be easily filtered out.

Benefits of the Active PFC Technique

Active PFC techniques can result in a power factor of 0.95 or better. They also use small and lightweight components that don’t significantly impact the weight and size of the product. Active PFC provides constant intermediate voltage to the DC/DC converter, which simplifies the complexity and requirements of the converter.

Active PFC is a versatile technique that is compatible with input voltages from 87 Vrms to 266 Vrms and frequencies from 47 Hz to 63 Hz without switching. This technique also provides greater control and flexibility, as it has two modes: continuous and comparative. The continuous mode is ideal for high-power applications, while the comparative mode is suitable for lower-power applications.

Pros and Cons of Active Power Factor Correction

To decide whether active power factor correction is right for your application, consider the pros and cons.

Pros:

• Achieves power factor of at least 0.95
• Good flexibility and control
• Compact and lightweight
• Works with a range of input voltages from 87 Vrms to 266 Vrms and frequencies from 47 Hz to 63 Hz

Cons:

• Higher cost
• High complexity
• Requires components rated for higher voltages than passive PFC techniques
• Requires more noise filtering due to higher frequencies

Types of PFs

There are two common types of power factor to account for: distortion PF and harmonics PF. Both combined represent the true power factor.

Distortion PF

The distortion power factor describes how much the total harmonic distortion in a nonlinear load decreases the total amount of power delivered to the load. In three-phase electrical systems, each of the three loads may fall out of phase or lag. To address this, manufacturers can use a capacitor to minimize the distortion.

Harmonics PF

The harmonic power factor is caused by the nonlinear switching of the supply voltage that comes from using rectifiers or semiconductors.

Industries That Use Active PFC

Active PFC offers unique benefits to many industries, including:

• Computers. Workstation and desktop computer manufacturers use active PFC to achieve energy efficiencies of at least 95% and meet critical Energy Star standards.
• HVAC. In HVAC systems, variable-speed drives use active PFC to manage fans and compressors. Power factor correction is key to most rectifier designs to comply with regulations limiting the harmonic content of input currents.
• Industrial. Active PFC is used in industrial power supplies for construction equipment, factory automation, power utilities and generation, and more.
• Military. Custom power supplies for military planes, ships, and other platforms also rely on active PFC circuits. In these applications, the electronic system appears as a resistive load, minimizing the risk of interference.

Active PFC Inductors

Active PFC solutions, such as PFC inductors, make electronics more efficient. Current can lag behind voltage, lowering the device’s power factor. PFC inductors correct the phase angle between the current and the voltage, thereby enhancing power quality and boosting the power factor.

PFC Products From MPS Industries

For producing high-power, high-efficiency electronic assemblies, manufacturers need active power factor correction hardware to reduce energy loss and bolster power quality. MPS Industries specializes in power factor correction inductors that correct displacement and distortion. As an ISO 9001:2015 and ISO 14001:2015 certified manufacturer, we provide high-quality magnetic components to leading organizations in the automotive, aerospace, military, medical, and other critical industries.

Request a quote to get started with your PFC inductor solution.