Choosing IGBT (Insulated Gate Bipolar Transistor) and MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as power switching devices is a decision that requires careful consideration of application requirements, performance characteristics, and localization factors. The following is an original and logically clear analytical framework:
Core difference: Understanding the essence of two devices
IGBT：
Structure: Combining the characteristics of MOSFET (voltage controlled gate) and BJT (bipolar junction transistor, high current capability).
Advantages:
High voltage/high current capability: Very suitable for handling high voltage (usually above 600V, up to several thousand volts) and medium to high current applications.
Low conduction voltage drop: Under high voltage and high current, the voltage drop in its conduction state is usually significantly lower than that of MOSFETs of the same voltage level, which means lower conduction loss.
High current density: capable of handling larger currents within the same silicon wafer area.
Disadvantage:
Slow switching speed: Due to the minority carrier storage effect, the switching frequency (especially turn off) is lower than MOSFET. This limits its use in high-frequency switch applications.
High switching losses: Slow switching speeds result in higher energy losses per switch.
There is tail current: a unique phenomenon during shutdown, which further increases shutdown losses.
Negative pressure shutdown is required: Some high-voltage applications or to improve anti-interference ability, the drive circuit may require negative voltage to ensure reliable shutdown.
MOSFET：
Structure: Pure unipolar device (conducting most charge carriers).
Advantages:
Extremely high switching speed: The switching frequency can reach the MHz level, and the switching time is very short.
Low switching loss: Thanks to high-speed switching, the energy loss per switch is very low. This is its core advantage in high-frequency applications.
Pure voltage control: simple gate drive and extremely low power consumption. Usually only unipolar positive voltage drive is required (turn on positive voltage, turn off 0V or negative voltage).
No secondary breakdown: The safe working area is more spacious.
Disadvantage:
High on resistance: As the rated voltage of the device increases, its on resistance increases exponentially. This results in significant conduction losses and a sharp decrease in efficiency under high voltage (especially>400V) and medium to high current applications.
High cost of high voltage and high current: To meet the demand for high voltage and high current, a very large chip area or complex parallel connection is required, which is costly.
Key considerations for choosing in the UK (taking into account local conditions)
Application scenarios and core parameters:
Voltage level (V):
<200V: MOSFET is almost always chosen. It has low conduction loss and excellent switching performance.
200V-400V: Key trade-off range.
If the current is small or the switching frequency is high ->MOSFET may be better (switching losses dominate).
If the current is high and the switching frequency is low ->IGBT may be better (conduction loss dominant).
SiC MOSFET is a strong competitor in this range, especially in efficient and high-frequency applications, but at a higher cost.
>600V: IGBT is usually the default selection. The on resistance of MOSFET at this voltage is too high, and the loss is difficult to accept.
Current level (A): When high currents (over tens of amperes) are applied at higher voltages, the conduction loss advantage of IGBT is more obvious.
Switching frequency (kHz):
Low frequency (<20kHz): The conduction loss advantage of IGBT can usually compensate for its higher switching loss. Like traditional power frequency motor drive UPS。
Intermediate frequency (20kHz -100kHz): requires careful calculation and simulation. The conduction loss advantage of IGBT vs the switching loss advantage of MOSFET. The competition between Si IGBT and Si MOSFET is fierce in this range, and the advantages of SiC MOSFET are beginning to emerge.
High frequency (>100kHz): The switching loss advantage of MOSFETs (especially SiC/GaN) becomes the decisive factor. Such as switching power supplies, high-frequency induction heating, and high-efficiency DC-DC converters. Traditional Si MOSFETs have poor efficiency at high frequencies and voltages.
Efficiency requirements:
Light load efficiency is important: MOSFETs have relatively low conduction losses (proportional to the square of the current) at light loads, which may be more advantageous.
Full load efficiency is important: IGBT usually has higher efficiency (lower conduction loss) at high voltage and high current full load.
Topology structure: Switching losses are more critical in hard switching topologies, while soft switching topologies (LLC, PSFB, etc.) can significantly reduce switching losses, which may make IGBT more competitive in high voltage and high current applications.
Unique environmental and market factors in the UK:
Climate and heat dissipation: The climate in the UK is relatively mild, but humid environments require corrosion protection for radiators. IGBTs typically require more complex heat management (due to concentrated switching losses), while MOSFETs may have a more uniform heat distribution (dispersed conduction losses). When designing, it is necessary to consider the cost of heat dissipation and reliability.
Grid standard: The UK standard voltage is 230V (+10%/-6%), and the single-phase and three-phase industrial voltage standards are similar to other European countries. The selection of devices must meet relevant safety certifications (such as IEC/EN standards).
Environmental regulations and energy efficiency standards: The UK (and EU inherited) has very strict energy efficiency requirements for electronic devices, such as the ErP Directive. Efficiency is the core consideration. This has driven:
In traditional IGBT advantageous fields such as motor drives and industrial power supplies, more advanced IGBT technologies such as Field Stop and Trench Gate are used to improve efficiency.
Accelerate the popularization of MOSFET/SiC MOSFET advantages in areas such as server power supplies and high-efficiency chargers.
Carbon footprint awareness: The increasing demand for efficient and low-energy products from industry and consumers affects device selection.
Supply Chain and Cost:
Supply stability: Evaluate the inventory and delivery time of required models by UK distributors such as Farnell, RS Components, DigiKey UK, Mouser UK. Global supply chain fluctuations may affect the supply of specific components.
Local support: Is there local FAE (on-site application engineer) support? This is important for complex design debugging.
Cost sensitivity: How sensitive is the project budget to device costs? IGBT modules may be cheaper than discrete MOSFET arrays with equivalent capabilities (especially in high voltage and high current), but the cost of driving circuits should also be taken into account. SiC/GaN devices have excellent performance, but their unit price is significantly higher than that of Si devices.
Total cost of ownership: Consider the long-term electricity savings brought about by efficiency improvements (especially important in industrial and high-power applications).
The impact of emerging technologies (SiC&GaN):
SiC MOSFET: rapidly growing in the UK market. It combines the high-speed switching advantage of MOSFET with the conduction characteristics superior to Si IGBT, especially under high voltage. It is a disruptive choice in high voltage (650V, 1200V, 1700V+), high-frequency, and high-efficiency applications (such as electric vehicle charging stations, solar inverters, high-end industrial power supplies), and can significantly reduce both conduction and switching losses. Although the initial cost is high, the system level advantages it brings (improved efficiency, reduced heat sinks, reduced magnetic components) and long-term energy-saving benefits are becoming increasingly attractive under the strict energy efficiency requirements in the UK.
GaN HEMT: It mainly exhibits significant advantages in applications with medium to low voltage (<650V) and ultra-high switching frequency (MHz), such as fast charging adapters, data center server power supplies, and laser radar. It has wide applications in the consumer electronics and high-end computing markets in the UK.
Summary of Decision Process
Clarify core requirements: Determine the voltage, current, switching frequency range, efficiency goals (especially for light/full load), topology, size limitations, and budget for the application.
Preliminary screening:
Voltage<200V ->Si MOSFET is preferred.
Voltage>600V ->IGBT or SiC MOSFET are preferred.
Voltage 200-600V, high current/low frequency ->Focus on IGBT and SiC MOSFET.
Voltage 200-600V, low current/high frequency ->Focus on Si MOSFET and SiC MOSFET/GaN HEMT.
In depth analysis and weighing:
Perform detailed loss calculation and simulation (conduction loss+switching loss), compare the total loss and temperature rise of different device schemes at the target operating point.
Evaluate the complexity and cost of the driving circuit.
Evaluate the complexity and cost of the cooling solution (considering the UK environment).
Evaluate system level benefits (value brought by efficiency improvement, size reduction, and weight reduction).
It is essential to consider the SiC/GaN solution: even if the initial cost is high, its system level advantages and long-term energy-saving benefits may make it superior in total cost of ownership, especially in line with the UK's high energy efficiency requirements.
Consider localization factors:
Check the supply situation and prices of major distributors in the UK.
Confirm that the device meets relevant safety and energy efficiency certifications in the UK/EU.
Assess supply chain risks and local technical support capabilities.
Make a choice: Based on a comprehensive balance of technical performance, cost (initial+TCO), reliability, supply, local support, and other factors, select the most suitable device (Si MOSFET, Si IGBT, SiC MOSFET, GaN HEMT).
Conclusion
There is no universal answer to choosing IGBT or MOSFET (or more modern SiC/GaN) in the UK. The key is:
High voltage (>600V), high current, mid low frequency: IGBT is still a mature, reliable and cost-effective main choice. But SiC MOSFETs are rapidly penetrating this market with their excellent performance.
High current and medium frequency in medium voltage (200-600V): IGBT vs Si MOSFET vs SiC MOSFET fiercely compete, requiring accurate calculation of losses. SiC MOSFET has significant performance advantages in this range.
Medium low voltage (<600V), high frequency, pursuit of ultimate efficiency: MOSFET (Si, especially SiC, GaN) is the preferred choice. SiC MOSFET and GaN HEMT represent the future direction.
Low voltage (<200V), high frequency: Si MOSFET is the absolute mainstream.
The UK market has a high acceptance of energy efficiency, environmental protection, and emerging technologies (SiC/GaN). When designing new products, it is important to carefully evaluate the potential system level advantages brought by SiC MOSFET and GaN HEMT, even if their unit price is high, which may have significant value in meeting strict energy efficiency regulations in the UK and reducing long-term operating costs. Meanwhile, closely monitoring the supply chain stability and local technical support level of major distributors in the UK is also a key factor for success.