Comparing SIC and IGBT Technology In Active Harmonic Filters

Introduction to Active Harmonic Filters

Power quality is a major cause for concern for residential and industrial setups in the modern world. A major deterrent to power quality happens to be harmonic distortion. This phenomenon occurs when a non-sinusoidal waveform is created in the circuit because of non-linear loads. Unfortunately, most modern devices, such as variable frequency drives, produce a lot of non-linear load, leading to the generation of extreme harmonics.

Why are harmonics such a cause for concern? It lies mainly in the effect it causes in the electrical system. Some common adverse effects include overheating and damage to sensitive equipment, reduction in power quality and therefore energy efficiency, and requiring oversizing of equipment to compensate. This is why it is vital to reduce this distortion, and active harmonic filters emerge as one of the best solutions. By mitigating harmonics and keeping them well below the acceptable level, it enables facilities to properly utilize their power, protect their equipment from overheating, and make sure that they stay well within the standards of international power quality, namely IEEE-519.

Now, coming to the active harmonic filters themselves, they mainly use two types of harmonic mitigation technology. One is the IGBT technology used in most conventional harmonic filters, and the other is SiC technology, which is seeing widespread use in more modern iterations of the active harmonic filters. This blog will cover the basics of these two technologies and compare their major pros and cons, as well as applications in power quality solutions.

Understanding IGBT Technology in Active Harmonic Filters

What is an IGBT and How It Works in Power Electronics?

IGBT stands for Insulated Gate Bipolar Transistor, a form of technology used in most active harmonic filters in the past. The main function of an IGBT in active filters is to control the compensation current generated in the harmonic filter that is used to counteract the incoming harmonic current. Here’s a detailed look at how an IGBT functions with respect to active harmonic filters and power electronics:

- Sensing: The incoming harmonic distortion is monitored by the harmonic filter, and its magnitude and phase are measured.

- Signal processing: The current signals of the incoming harmonics are converted into a digital signal, which is in turn used to determine the compensation current required to counter the harmonics.

- Control logic: The control logic part of the active harmonic filter determines how much and when the compensating currents will be released as required.

- IGBT switching: This is where IGBTs become relevant in active harmonic filters. Based on the control signals sent by the control logic, the IGBT functions as a switch. When turned on, it allows the flow of compensating current, and when turned off, the flow of current is stopped.

- Harmonic mitigation: As the compensation current is equal in magnitude but opposite in phase, it cancels out the harmonic distortion and ensures proper mitigation.

Advantages of IGBTs in Active Filters

Some of the biggest advantages with respect to IGBTs in active harmonic filters include:

Cost-effectiveness

IGBTs are one of the most cost-effective electronic solutions used in active harmonic filters, especially when compared to other similar power electronics solutions.

Robustness

IGBTs are also quite robust in nature. They can handle high power levels with ease. This means that in applications where there is significant harmonic distortion, it can perform its functions properly without facing major wear and tear.

Wide adoption and availability

Lastly, IGBTs are used widely in harmonic filters and are easily available should they require replacement. A big reason behind this widespread adoption is its cost-effectiveness, good efficiency, and robust design to handle power and a high level of harmonics.

Limitations of IGBT Technology

Switching Losses

Since IGBTs perform as a switch, they lose energy every time they change states. Therefore, during frequent operation, it can lead to some decent energy loss.

Thermal management challenges

Even after their robust design, IGBTs run the risk of overheating with constant operation, which can eventually damage components and lower their performance and lifespan.

SiC Technology and Its Role in Active Harmonic Filters

What is SiC (Silicon Carbide) in Power Semiconductors?

Silicon carbide in power electronics, also known as SiC, has emerged as an alternative to IGBTs. It is a form of wide-bandgap semiconductor that is used mainly to control and switch electronic devices, much like an IGBT. However, they perform switching at a much faster rate, tolerate higher operating temperatures and improve overall system efficiency. Here’s how they operate:

- Gate control: SiC MOSFETS, which are used in harmonic filters, operate by applying voltage to the gate terminal. This creates an electric field between the voltage source and the drain terminals.

- Wide band gaps: Due to the wide bandgap properties of SiC, it can handle higher electric fields and more voltage.

Advantages of SiC in Active Filters

Incorporating SiC technology in active harmonic filters has some undeniable advantages, including:

High switching frequency

The SiC system used in active harmonic filters allows it to switch between on and off states with a very high frequency. This means that it is not limited to power levels and loads, and can perform this task indefinitely.

Reduced losses

Another major benefit, perhaps the biggest advantage of SiC technology, is that it offers very limited losses of energy when switching. This directly addresses one of the biggest cons of the IGBT system used in conventional active harmonic filters.

Compact design possibilities

Since it can handle high voltages and temperature fluctuations, as well as switching frequency, it can allow active harmonic filters to be more compact without losing any of their performance characteristics.

Limitations of SiC Devices

While SiC is the latest technology used in active harmonic filters, it comes with its own set of drawbacks.

Higher initial cost

When compared to IGBT systems, SiC is significantly more expensive. This lack of cost-effectiveness means that it will increase the cost of production of the harmonic filter as well.

Supply chain maturity concerns

Similarly, since SiC is used less frequently than IGBT, it can cause some problems in the supply chain. There is more likely to be a shortage in its supply chain, making constant procurement a challenge.

SiC vs IGBT in Active Harmonic Filters – Key Differences

Between SiC and IGBT, which fares better? Here’s a key comparison of SiC MOSFET Vs IGBT.

Efficiency and Power Loss

In terms of energy efficiency, SiC harmonic filters have an upper hand when compared to IGBT filters. The difference mainly lies in the difference in energy losses. While energy losses due to frequent switching are a major cause for concern for IGBT filters, this problem is directly addressed with their SiC counterparts. Thereby, it contributes to more efficiency and a reduction in power loss.

Switching Frequency and Thermal Performance

When it comes to switching frequency, SiC is superior to IGBT once again. It can easily switch at a very rapid pace with minimal energy losses when compared to IGBT active harmonic filters. This also reflects in its overall thermal performance. Overheating due to switching losses can reduce the lifespan of IGBT filters despite their robust design. But since SiC filters can easily handle switching and have a higher temperature tolerance than IGBT filters, they win out in this department too.

System Size and Design Optimization

The compactness of the active harmonic filter is a major consideration when it comes to design optimization. How do the two technologies fare in this regard? IGBT filters dissipate more heat due to switching losses. This means that they require a bigger heat sink to keep the temperature from rising too much, and this will negatively impact the compactness of the filter. SiC filters, on the other hand, handle heat much more effectively, require a much smaller sink, and thereby, enable the filters to be designed in a much more compact manner.

Cost and ROI Considerations

This is the only factor where IGBT active harmonic filters are considered a better choice. Since they are more cost-effective and readily available, they can have an initial lower investment. However, once the return on investment (ROI) is taken into consideration, the distinction is not so prominent. SiC harmonic filters, although expensive initially, offer better ROI in the long term as they offer better energy efficiency, better temperature control, and a compact design.

Reliability and Longevity

As SiC harmonic filters offer better tolerance to heat, significantly improved energy efficiency, and more advantages, they also offer an edge over IGBT filters in terms of longevity. Although IGBT filters are quite robust, SiC harmonic filters have an upper hand here in terms of durability, longevity and reliability.

Application Scenarios – When to Choose SiC or IGBT

To better demarcate between the two systems, here are 3 cases where their applications are clearly defined:

Case 1: Industrial plants with high current demand

Industrial plants can utilize a wide variety of equipment, such as robotics, UPS systems, welding/plasma cutting applications and more. All of these applications have a high current demand, and thereby require robust active harmonic filters to tackle significant harmonics. Although IGBT filters can work here, SiC filters are clearly the better power semiconductor device for filters in this case. However, if cost effectiveness is a huge factor, then IGBT can be considered.

Case 2: Renewable energy integration

The renewable energy sector faces harmonics when dealing with energy storage and integrating this power into the main grid. Therefore, they require an active harmonic filter that is highly reliable and effective. So by these metrics, SiC-based harmonic filters are the better choice yet again.

Case 3: Data centers requiring compact, efficient solutions

Data centers not only require a reliable harmonic filter to eliminate instances of data loss, but they also need to be compact, as spatial constraints are a major factor. With this in mind, SiC harmonic filters are a clear winner as they not only offer excellent efficiency and reliability, but it also make it feasible to design more compact harmonic filters as it has superior heat dissipation features.

Future Trends in Active Harmonic Filter Technology

Here are some trends to watch out for in the future regarding active harmonic filters:

- Growing adoption of SiC: With more distinct advantages of SiC technology over IGBT, there is a clear-cut rise in the adoption of the former among active harmonic filter manufacturers.

- Hybrid designs combining IGBT + SiC: If SiC technology is too expensive for a harmonic filter, many manufacturers can also adopt a more hybrid design, featuring both IGBT and SiC systems.

- Industry shift toward compact, high-efficiency systems: The harmonic filter industry is also shifting more towards compact, high-efficiency systems.

How Revcon Active Filters Support Modern Power Systems?

Revcon Active Filters offered by ADM Engineering Inc., in Miami, Florida, provide advanced solutions for harmonic mitigation, designed with SiC-based technologies that surpass the conventional harmonic filters in terms of noise reduction, efficiency, accuracy and more. Our active harmonic filters are designed to handle diverse industrial needs, ranging from HVAC systems, data centers, the marine industry, the medical sector, oil and gas production, and much more. For more details on our power quality solutions, contact us at 877-236-8337 today.