Introduction
Power semiconductor devices play a crucial role in efficient power conversion and management. Insulated Gate Bipolar Transistor (IGBT) and Super Junction MOSFET are two of the most widely used power devices. Both IGBT and Super Junction MOSFET are able to operate at much higher voltages than conventional MOSFETs, making them ideal for applications requiring high-power handling capability. In this article, we will explore the working principles, characteristics and applications of IGBT and Super Junction MOSFET along with comparing their pros and cons.
IGBT - The Workhorse of Power Electronics Industry
IGBT was developed in the 1980s as an improvement over bipolar junction transistors (BJT). It combines the simple gate-drive characteristics of MOSFET and the high current and low conduction loss benefits of bipolar transistor. IGBT has now become the most commonly used power semiconductor in medium to high power applications such as motor drives, solar inverters, uninterruptible power supplies and welding machines.
Working Principle of IGBT
An IGBT is basically a IGBT And Super Junction MOSFET p-n junction between the gate and drain terminals. When a positive voltage is applied to the gate, an inversion layer is created due to which electrons flow from the source to the drain. However, unlike a MOSFET the current is amplified in an IGBT due to the presence of the p-n junction. When the gate signal is removed, the IGBT remains on until the charge stored in the p-n junction is removed, thus exhibiting the switching behavior of a bipolar junction transistor.
Advantages of IGBT
- High input impedance and ease of drive similar to MOSFET
- Lower conduction losses compared to BJT due to majority carrier conduction
- Suitable for high current, high voltage switching applications in medium power range
- Widely available in the market and proven record of reliability
Disadvantages of IGBT
- Slower switching speeds than MOSFET leading to higher switching losses
- Requires a gate drive circuit for turn ON and OFF
- Prone to damage if short circuited due to high peak current during turn OFF
- Storage time of minority carriers adds to switching delays
Super Junction MOSFET - The New Kid on the Block
Super Junction MOSFET was introduced in the early 2000s as an improvement over traditional MOSFETs. It addressed the limitations of conventional MOSFET such as lower voltage blocking capability at higher current ratings. Through the use of alternating layers of n-type and p-type epitaxial material during fabrication, super junction MOSFET achieves high blocking voltage with negligible increase in on-resistance.
Working Principle of Super Junction MOSFET
A super junction MOSFET has a multi-layered epitaxial drain drift region consisting of alternately doped n-type and p-type columns perpendicular to the top surface. When voltage is applied, the applied electric field ionizes the dopant atoms, creating space charges that cancel out the longitudinal electric field. This allows the device to support high blocking voltages even with low doping concentrations, thereby reducing conduction losses.
Advantages of Super Junction MOSFET
- Much higher blocking voltage (>650V) compared to conventional MOSFET
- Lower specific on-resistance enabling high current switching
- Faster switching speeds compared to IGBT due to majority carrier transport
- Ease of drive and simplified gate drive circuitry
- Reduced conduction and switching losses leading to higher efficiency
Disadvantages of Super Junction MOSFET
- More complex fabrication process than traditional MOSFET
- Higher cost compared to IGBT
- Prone to dynamic on-state resistance variation due to charge imbalance
- Limited voltage ratings compared to IGBT
Comparison and Application Areas
Both IGBT and Super Junction MOSFET have their unique characteristics suitable for different applications. IGBT is commonly used in medium-high power range (100V-6500V) applications requiring high current handling. Due to lower losses, Super Junction MOSFET has gained popularity in very high frequency (<500kHz) applications up to 1200V where switching losses dominate. Some key differences are:
- On-state conduction losses - IGBT has an edge due to majority carrier conduction. But advances are bringing SJ MOSFET at par with IGBT.
- Switching losses - SJ MOSFET is clearly superior due to majority carrier transport and higher switching speeds.
- Gate drive complexity - SJ MOSFET is much simpler to drive than IGBT.
- Cost - IGBT is relatively cheap for medium power. But SJ MOSFET expected to outpace IGBT in high power, high voltage range.
Some common application areas where these devices are used include motor control, solar inverters, UPS, industrial motor drives, electric vehicles, energy storage systems and power supplies. With technology improvements, the boundaries between their application areas are also evolving.
Conclusion
Both IGBT and Super Junction MOSFET will continue to co-exist and find new areas of applications. While IGBT dominates medium power range, SJ MOSFET is gaining ground in very high frequency designs. Manufacturers are working towards enhancing their voltage and current ratings as well as reducing losses. The future promises even more efficient utilization of these powerhouse devices for enabling greener and smarter power systems.
Get more insights, On IGBT and Super Junction MOSFET
A switching power supply may be required to convert energy or power from one level to the next.Products around your house are using power switching supplies whether you realize it or not.
They convert the power coming in from the wall to a lesser voltage suitable for a given appliance or device.
Linear and switching power supplies are both on the market today.Linear power supplies rely on the primary transformer as they convert alternating electric current into direct current voltage.
This sort of linear power supply can be long and heavy, so it’s wasting energy and time in the operation.What brings people to choose switch mode power supplies is that they are efficient.
They can transform the alternating current without jumping back to the main transformer.
Voltage changes quickly.Switching PSUs do not burn heat.
