1. Efficiency (especially switch losses):
SiC MOSFET: The biggest advantage lies in its extremely low switching losses (on and off processes). It does not have the tail current problem of IGBT, and the switching speed can be made very fast. This makes it significantly more efficient than IGBT in high-frequency switching applications (such as>20kHz, even above 100kHz).
IGBT: The conduction loss (at rated current) is usually lower or equivalent to SiC MOSFET, but its switching loss, especially the turn off loss and tail current loss, will sharply increase at high frequencies, leading to a decrease in overall efficiency.
Alternative impact: In applications that require high efficiency (such as electric vehicle drivers, data center power supplies, photovoltaic inverters) or must operate at high frequencies (such as compact chargers, high-end server power supplies), replacing SiC with IGBT will significantly reduce system efficiency and generate more heat. In order to achieve the same output power, larger heat sinks may be required, increasing volume and cost. In extreme cases, IGBT may not be able to meet efficiency requirements at all.
2. Working frequency:
SiC MOSFET: can easily operate at frequencies of 50kHz, 100kHz, and even higher.
IGBT: Although the new generation IGBT can also operate at higher frequencies (such as 30-50kHz), the higher the frequency, the greater the proportion of switching losses, the sharp decrease in efficiency, and the faster the temperature rise, which limits its practical application frequency limit.
Alternative impact: If the application requires high switching frequency to achieve smaller magnetic components (inductors, transformers) and higher power density (smaller volume), IGBT usually cannot effectively replace SiC. Forcing IGBT to operate at SiC frequency can lead to overheating and reliability issues.
3. High temperature performance:
SiC MOSFET: Silicon carbide material itself has a higher bandgap, higher thermal conductivity, and higher critical breakdown electric field. This enables SiC devices to operate at higher junction temperatures (typically 175 ° C or higher) with less performance degradation at high temperatures.
IGBT: The maximum junction temperature of silicon-based IGBT is usually limited to 150 ° C or 175 ° C (some models), and the conduction voltage drop and switching loss will increase more significantly at high temperatures.
Alternative impact: In high-temperature environments or applications with strict heat dissipation requirements (such as reducing heat sinks), SiC has significant advantages. Replacing IGBT may require a stronger cooling system.
4. Conduction loss:
IGBT: At moderate current densities, the conduction voltage drop is usually low (especially in models with optimized conduction characteristics).
SiC MOSFET: The on resistance continuously decreases with the development of technology. At low currents, its conduction voltage drop may be higher than IGBT (because IGBT has a PN junction voltage drop of about 0.7V, while MOSFET has pure resistance characteristics), but at medium and high currents, the conduction loss of modern SiC MOSFET is already very close to or even better than IGBT of the same specifications, especially at high temperatures where the advantage is more obvious.
Alternative impact: In low-frequency, high current applications where conduction losses dominate (such as certain industrial motor drives), IGBT may still have advantages or remain unchanged. But after comprehensive switch losses, SiC usually has better overall efficiency.
5. Cost:
Current status: The unit price of SiC modules (especially high current/high voltage modules) is still significantly higher than IGBT modules of the same voltage/current level (usually several times higher). This is currently the biggest obstacle to SiC fully replacing IGBT.
From a system cost perspective: Although SiC modules themselves are more expensive, they can bring:
Higher system efficiency: Reduce operating electricity costs (for high-power or long-term operating equipment, the saved electricity costs may quickly cover the price difference of components).
Higher power density: reduce the size and cost of passive components such as heat sinks, filters, transformers, inductors, etc.
Smaller cooling system: may reduce the cost of fans, radiators, and even casings.
Alternative impact: If we only look at the cost of device procurement, replacing SiC with IGBT is a direct means of cost reduction. But if we consider the overall system cost (BOM+manufacturing cost) and lifecycle cost (operating electricity cost), in many mid to high end applications, using SiC may actually have an advantage in total cost, especially in applications that are sensitive to efficiency, size, and weight (such as electric vehicles).
6. Voltage level:
Both cover commonly used voltage platforms such as 600V, 1200V, 1700V, etc. The advantages (efficiency, frequency) of SiC at voltages of 1700V and above are more significant compared to IGBT. In higher voltage fields such as 3300V and 6500V, SiC is the superior or even the only choice (silicon-based IGBTs perform poorly at these voltages).
Conclusion:
1. Cannot be simply replaced (high-performance/high-frequency applications): SiC modules have irreplaceable advantages in applications that pursue ultimate efficiency, high power density, high operating frequency (>50kHz), high operating temperature, or high voltage (>1700V). IGBT modules cannot provide equivalent performance in these scenarios.
2. Can be replaced, but at a cost (cost sensitive/low-frequency applications): In applications that are extremely cost sensitive, have low switching frequencies (such as<20kHz), do not require the highest efficiency, have good heat dissipation conditions, and have limited system size and weight, using mature IGBT modules instead of SiC modules is a feasible cost reduction solution.
3. Possible lower system efficiency (higher operating costs).
4. Larger system volume and weight (larger heat sinks and magnetic components).
5. Lower power density.
6. Possible stricter thermal management requirements.
7. Substitution is a two-way dynamic: as SiC technology matures, production capacity increases, and costs continue to decline, its cost-effectiveness advantage continues to expand, accelerating its market share in replacing traditional IGBTs, especially in key areas such as new energy vehicles, photovoltaics, energy storage, and high-end industrial power supplies. At the same time, IGBT technology is constantly advancing (such as microgroove gates, reverse conduction type, etc.), striving to improve performance and frequency limits to consolidate its position in cost sensitive fields and specific mid to low frequency applications.
