How Silicon Carbide Maximizes Efficiency of Renewable Energy Systems

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The world is experiencing an energy revolution. According to the International Energy Agency, renewable energy will account for approximately 95% of global energy growth by 2026. Solar energy will account for more than half of this 95%.

Today, driven by ambitious clean energy goals and government policies, the adoption of renewable energy in solar, electric vehicle (EV) infrastructure and energy storage continues to accelerate. The increasing popularity of renewable energy also provides more opportunities for the deployment of power conversion systems in industrial, commercial and residential applications. The use of wide bandgap devices such as silicon carbide (SiC) can help designers balance the four major performance indicators: efficiency, density, cost and reliability.

Advantages of SiC over traditional IGBT-based power supplies in renewable energy systems

SiC power switches and insulated gate bipolar transistors (IGBTs) are commonly used power switches for high-power applications such as renewable energy systems. Figure 1 shows the typical switching frequencies and power levels of SiC power switches and IGBTs. Both are suitable for power levels of 1kW and above.

Figure 1: Typical operating range of a power switch

SiC power switches offer many performance advantages over traditional silicon power switches such as IGBTs in high-power renewable energy applications.

The first performance advantage is lower resistance and capacitance compared to IGBTs, which reduces power losses and helps improve efficiency. SiC power switches can support much higher switching speeds than IGBTs, helping to reduce switching losses and improve power conversion efficiency. This means higher energy production, maximizing the output of power converters, which is critical in renewable energy systems such as photovoltaic inverters, energy storage systems or DC fast charging power modules.

Many renewable energy applications operate in a small area, generating a lot of heat, driving designers to continually explore ways to reduce the size of printed circuit boards and maximize heat dissipation. SiC operates at a higher temperature than IGBTs, making SiC power switches more thermally and mechanically stable, enabling more compact power electronics designs.

Driving SiC with Gate Drivers

Driving SiC power switches requires special considerations due to their characteristics. The gate driver selection will have a reasonable impact on the performance of SiC in the application.

SiC power switches require gate drivers that can handle high voltages and current ratings. The gate driver must provide enough gate charge to switch the SiC power switch and prevent voltage spikes.

Compared to IGBTs, SiC power switches are more susceptible to short circuits, which can cause serious damage to power electronic systems. Typically, IGBTs have a short circuit withstand time of about 10s, while SiC has a short circuit withstand time of about 2s. Given this, when designing with SiC power switches, it is important to consider adding protection components that provide features such as desaturation or overcurrent protection. Some gate drivers, such as the UCC21710 gate driver, have built-in short-circuit protection features that can detect and respond to short-circuit events.

Although SiC power switches can operate in higher temperature environments, it is still very important to monitor the thermal performance of SiC power switches and prevent overheating. In addition to the built-in short-circuit protection feature, the UCC21710 also has an integrated sensor for monitoring, eliminating the need to deploy a discrete temperature sensor.

Conclusion

To fully exploit the power output of renewable energy systems, efficiency must be maximized while balancing cost, size, and reliability. SiC power switches offer many advantages in high-power applications, making them ideal for solar and electric vehicle charging.