Which is better: IGBT or MOSFET? A detailed comparison for understanding and choosing

 

In the field of power electronics, the question often arises when designing or selecting equipment: which is better—IGBT or MOSFET? This question is especially relevant for specialists working with converters, welding machines, power supplies, inverter systems, and other devices that require efficient power management. The correct choice between IGBTs and MOSFETs directly impacts the reliability, efficiency, and cost of the final device.

To answer this question, it's necessary to thoroughly understand the operating principles of both types of transistors, compare their characteristics, applications, advantages, and disadvantages. This article will provide a detailed technical and practical comparison of IGBTs and MOSFETs to help you choose the optimal solution for your specific application.

Basics: What are IGBTs and MOSFETs?

MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)A MOSFET is a field-effect transistor with an insulated gate. It operates using an electrostatic field, controlling the current between the source and drain. MOSFETs have extremely low inertia and high switching speed, especially in the range from 0 to 200 V.

IGBT (Insulated Gate Bipolar Transistor)A MOSFET is a semiconductor device that combines the structure of a MOSFET and the characteristics of a bipolar transistor. It has the high input resistance of a MOSFET, but also the high current-carrying capacity of a bipolar transistor.

Key Features

Let's consider the main parameters that influence the choice:

Operating principle and differences

MOSFETs are gate-voltage-controlled: when a positive voltage is applied between the gate and source, the channel between the source and drain becomes conductive. This makes MOSFET control simple and very fast.

IGBTs are also gate-voltage-controlled, but due to their bipolar structure, switching is accompanied by the accumulation and removal of charge carriers, which slows down the turn-off process. However, in conduction mode, IGBTs exhibit lower losses, especially at high currents.

Advantages and disadvantages

Advantages of MOSFET:

• Very fast switching
• Lower switching losses
• Easy to operate
• Suitable for high frequency applications

Disadvantages of MOSFET:

• High losses in the conducting state at high currents
• Limited operating voltage (up to 1000 V)
• Increased risk of breakdown during sudden voltage surges

Advantages of IGBT:

• High power and voltage capability
• Low conductive losses at high currents
• High overload resistance

Disadvantages of IGBT:

• Slower switching
• Increased switching losses
• Less efficiency at high frequencies

Application areas

MOSFET transistorsare used in:

• Switching power supplies
• DC-DC converters
• High frequency welding machines
• Electronic keys and relays
• Inverters for solar panels and battery systems

IGBT transistorsfind application in:

• Power inverters (e.g. frequency converters)
• Electric transport systems (trains, trams, elevators)
• High power industrial installations
• Grid-tie inverters for wind energy
• Traction converters

Comparison in practice

Let's consider a hypothetical problem: we need to build a 10 kW converter with an operating voltage of 800 V and a switching frequency of 20 kHz. In this case, an IGBT would be the preferred option because:

• It is resistant to high voltage.
• Provides lower losses at high power
• Better handling of temperature loads

If you are designing a converter for 500 V and 100 kHz, then the optimal solution would be a MOSFET:

• Its high switching frequency will allow the transformer and filter sizes to be minimized.
• The level of heat loss will be lower during high frequency operation.
• The cooling system will be simplified

Energy Losses: Who Wins?

At low currents and frequencies, both devices show comparable efficiency. However:

• MOSFETwins at frequencies above 50 kHz, where switching losses become critical.
• IGBTshows the best results in systems where the operating frequency is limited to 10–20 kHz, but the currents exceed tens of amperes.

In addition, IGBTs often implement protection functions against short circuits, overvoltage, and overheating, which makes them attractive for industrial solutions.

Heat dissipation and cooling

Despite high switching losses, IGBTs generate less heat at high currents than MOSFETs because their on-resistance is significantly lower. This allows for savings on heat sinks and heat dissipation systems under heavy loads.

MOSFET requires more efficient cooling when operating at high currents, especially in pulsed modes.

Price and cost-effectiveness

In low-voltage circuits (up to 200 V), MOSFETs are much cheaper and more efficient. However, as voltage and power increase, IGBTs become more advantageous in terms of price/reliability/loss ratio. This is especially true for industrial equipment.

The future of technology

The development of MOSFET production technologies based on wide-bandgap materials (for example, silicon carbide - SiC) and gallium nitride (GaN) has already made it possible to significantly improve their characteristics:

• Breakdown voltage up to 1200 V and higher
• Very low losses
• High switching frequency

However, IGBTs remain indispensable in ultra-high power applications where reliability and stability are required.

Conclusion

The answer to the question of which is better isIGBT or MOSFET, depends solely on the conditions of use:

• Choose a MOSFET, If:
  • High switching frequency (more than 50 kHz) is required
  • The operating voltage does not exceed 600–800 V
  • High response speed is important
  • The priority is compactness and energy efficiency
• Choose IGBT, If:
  • The working voltage exceeds 1000 V
  • The load current is significant (tens and hundreds of amperes)
  • The system operates at frequencies up to 20 kHz
  • Reliability and resistance to overload are important

Therefore, neither of these transistors is a universal solution. A sound choice relies on calculating characteristics, analyzing the application, and understanding the specifics of each device. In modern power electronics, the most effective solutions are built by combining the advantages of both transistor types within hybrid or specialized circuits.