Let's delve into the question of which is "better" between IGBT and MOSFET. It needs to be clear that there is no absolute 'better', only 'more suitable'. The choice of device depends on specific application scenarios, performance requirements, and cost considerations. The following is an original analysis of the characteristics and applicable scenarios of both:
Core difference: Structure and transmission mechanism
MOSFET (Metal Oxide Semiconductor Field Effect Transistor): It is a unipolar device. It mainly relies on a type of carrier (N channel is electrons, P channel is holes) flowing in the channel to conduct electricity. Its gate is controlled by voltage to turn on and off the channel, resulting in extremely low driving power.
IGBT (Insulated Gate Bipolar Transistor): It is a bipolar device. It is structurally equivalent to a MOSFET driving a bipolar junction transistor (BJT). Therefore, its conduction mechanism combines the voltage driving characteristics of MOSFETs and the low conduction voltage drop characteristics of BJTs (at high currents). It simultaneously utilizes both electron and hole carriers to conduct current.
Performance Comparison: Advantages and Disadvantages
Conduction losses:
Advantages of IGBT (medium high voltage/high current): Under medium high voltage (usually>600V) and high current conditions, the on voltage drop (Vce (sat)) of IGBT is significantly lower than the on resistance (Rds (on)) of high-voltage MOSFET of the same specifications. This is because IGBT utilizes the conductivity modulation effect of BJT, resulting in lower on resistance. This is the fundamental reason why IGBT has established itself in the field of medium to high voltage and high power.
Advantages of MOSFET (low voltage/low current): Under low voltage (usually<200V) and small to medium current conditions, the on resistance (Rds (on)) of MOSFET can be made very low, and its on loss (I ² Rds (on)) will be lower than that of IGBT (I Vce (sat)). With the advancement of technology, the Rds (on) of high-voltage MOSFETs are constantly decreasing, but their loss increase rate is usually still faster than the Vce (sat) loss of IGBTs at high currents.
Switching losses:
Advantages of MOSFET (high frequency): MOSFET is a unipolar device without minority carrier storage effect. Therefore, its switching speed is extremely fast (especially the turn-on speed), and the switching loss (especially the turn-on loss) is very low. This makes MOSFETs very suitable for high-frequency switching applications (tens of kHz to MHz).
Disadvantages of IGBT (low frequency): Due to its bipolar structure, IGBT has a tail current when turned off, which is caused by the recombination process of minority carriers. This significantly increases its turn off loss and limits its maximum operating frequency (typically in the range of several hundred Hz to tens of kHz, even optimized IGBTs are difficult to exceed 100 kHz). Its opening speed is also relatively slow.
Voltage level:
IGBT advantage (high voltage): IGBT has mature technology and cost advantages in the field of ultra-high voltage (such as 1700V, 3300V, 6500V or even higher). Manufacturing ultra-high voltage MOSFETs of the same voltage level is highly challenging in terms of technology and cost.
Advantages of MOSFET (low voltage): MOSFET is absolutely mainstream in the field of low and medium voltage (<1000V, especially<600V). At medium voltages (such as 600V-1200V), there is competition between the two.
Temperature characteristics:
MOSFET: Rds (on) has a positive temperature coefficient. This means that as the temperature increases, the on resistance increases, which helps to achieve natural current sharing between parallel devices and reduces the risk of thermal runaway.
IGBT: Vce (sat) typically has a negative temperature coefficient within the normal operating current range (positive temperature coefficient at low current, negative temperature coefficient at high current). This means that under high temperature and high current, the conduction voltage drop will decrease, which may lead to current concentration and potential local hotspot issues, requiring more cautious design for parallel applications.
Driver requirements:
Both are voltage driven devices with low gate driving current requirements and relatively simple driving circuits. But IGBT usually requires a slightly higher gate driving voltage than MOSFET (such as+15V/-8V vs+10V/0V or+12V/-3V, etc.).
Anti short circuit capability:
IGBT: typically has better short-term short-circuit resistance (such as a few microseconds to 10 microseconds), which is a key requirement for many industrial drive applications.
MOSFET: Its short-circuit withstand capability is relatively weak, and the current rises rapidly during a short circuit, making it more susceptible to damage. Very fast short circuit detection and protection circuits are required.
Summary: Who is more suitable for where?
Preferred application scenarios for MOSFETs:
Low voltage (<200V): such as laptop/phone chargers, DC-DC converters, battery protection boards, low-voltage motor drives (such as drones, power tools).
High frequency applications (tens of kHz to MHz): such as switch mode power supplies (SMPS), LLC resonant converters, wireless charging, and high-frequency induction heating.
Applications that require extremely high switching speed, such as synchronous rectification (SR) and certain types of motor drives that require high PWM frequencies.
Parallel applications that require natural current sharing capability.
Preferred application scenarios for IGBT:
Medium to high voltage (>600V)&high current: This is the "main battlefield" of IGBT.
Industrial motor drive: frequency converter (VFD), servo drive (medium high power).
Power transmission and conversion: uninterruptible power supply (UPS), solar inverters (centralized/series), wind power converters, high-voltage direct current transmission (HVDC).
Induction heating (medium high power/low frequency): such as metal melting.
Electric vehicles: main drive inverters (although SiC MOSFETs are rapidly penetrating, silicon-based IGBTs are still mainstream).
Welding equipment: high-power inverter welding machine.
Applications that require strong resistance to short circuits.
Emerging Trends: SiC and GaN
It is worth noting that the third-generation semiconductor devices (silicon carbide SiC MOSFET and gallium nitride GaN HEMT) are rapidly changing the landscape of power devices:
SiC MOSFET: combines the high-frequency switching advantages of silicon-based MOSFETs with low conduction losses that approach or even surpass silicon-based IGBTs (especially at 1200V and higher voltage levels), while exhibiting excellent high-temperature performance and thermal conductivity. It is rapidly eroding the market share of silicon-based IGBT in high-end applications such as electric vehicle main drives, high-efficiency solar inverters, high-end industrial drives, and data center power supplies.
GaN HEMT exhibits significant advantages in ultra-high frequency (above MHz) and ultra efficient medium to low voltage (<650V) applications, such as fast charging adapters, high-end server power supplies, and RF amplifiers.
Conclusion:
Is IGBT better than MOSFET? ”There is no universal answer to this question itself. IGBT has significant advantages in applications that require high voltage (>600V), high current, low to medium frequency, and a certain degree of short-circuit resistance, especially when cost remains a key factor. MOSFETs are unparalleled in low-voltage (<200V), high-frequency, and high-speed switching applications, and compete fiercely with IGBTs in the medium voltage field.
The final choice is a systems engineering issue that requires comprehensive consideration of:
Working voltage and current level.
Work frequency requirements.
Efficiency target (balance between conduction loss and switching loss).
Cooling conditions and cost constraints.
Reliability requirements (such as short-circuit resistance).
System volume and weight limitations.
The availability and cost-effectiveness of emerging technologies (SiC/GaN).
Excellent engineers will weigh the characteristics of IGBT and MOSFET (as well as SiC/GaN) based on specific application requirements, and choose the most suitable "chip doctor" to accurately manage power flow, rather than simply pursuing "better". With the continuous advancement of semiconductor technology, the performance boundaries between the two are also constantly evolving, and selection decisions need to keep up with the times.