Challenges in the Coming Market
The Electrification of Everything
Electrification is the process of replacing fossil fuels with electricity to reduce energy demand and emissions. The electrification of everything is creating many challenges in the upcoming market, as shown in Figure 1.
Figure 1: Challenges
The era of electrification of everything is being brought about by:
- Regulations
- Country Mandates
- International Agreements
- Sustainability
- Carbon Neutrality
- Net Emissions
- Zero Carbon Emissions
Countries are setting target dates and the industry is forced to meet these deadlines.
One of the ways the electrification of everything is being achieved is through sustainable transportation, such as electric vehicles. Aircraft and aviation are also being electrified. The goal is higher efficiency while reducing the reliance on fossil fuels and increasing our capacity using more net carbon-zero sources of power such as solar, wind, hydroelectric, geothermal, and others.
Thus, there is a need for energy efficiency across the board–in the electrical grid, our processes, buildings, homes, appliances, and our vehicles– not just in a particular power supply.
Energy Lifecycle
Figure 2 shows energy that is generated by different means and then it is conditioned. It is either increased in voltage for direct current (DC) transmission or alternating current (AC) transmission and then it's distributed across the country. It's reconditioned again for use in homes and factories and then consumed.
Figure 2: Energy Lifecycle
That's not just electricity, but it's energy in general.
U.S. Energy Consumption
Figure 3 shows the energy consumed a few years ago in the United States. On the left of the diagram, you have the sources of this energy:
- Solar
- Hydro
- Natural Gas
- Coal
- Petroleum
Figure 3: U.S. Energy Consumption
Figure 3 shows overall energy consumption, not just electrical. You can see petroleum goes into supplying energy for most of the transportation industry as well as industrial. The electric generation right now is going toward residential, commercial, and industrial.
In 2021, it was estimated that we in the United States used 4000 TWh of electricity.
The other important thing to consider is the rejected energy. This is energy lost in inefficiencies in transmission. It is wasted energy that was never used for actual work and accounts for about 65 percent of the energy that was generated. So there is a very low efficiency and that is something that can easily be improved.
Wide Band Gap Technology
We show in Figure 4 that going forward with the electrification of everything, it is estimated that an additional 2000 TWh of demand will be needed by 2050. This increase is mostly due to our reliance on electricity and the market going towards the electrification of everything.
Figure 4: Wide Band Gap Technology
Electric Vehicle Energy Consumption
So how does this show up in terms of energy consumption, in the United States? As shown in the Figure 5 diagram, 4000 TWh becomes 6000 TWh of electricity because of usage in the transportation industry. And there is still wasted, rejected energy.
Figure 5: EV Energy Consumption
This is demonstrating that there is a need to improve the conversion efficiency of our energy consumption.
Electrification Challenges
So what are some of the challenges? Refer to the accompanying Figure 6.
Figure 6: Electrification Challenges
There are challenges in improving the efficiency of our grid, sustainability and reducing wasted energy. This will help combat the rise in the cost of energy. Another one of the things we can do for this is to come up with higher system voltages which lowers the current.
Lower currents also reduce the losses inherent within transmission systems, solar systems and all sorts of distribution and energy creation.
In the Electric Vehicle (EV) market, battery voltages are trending higher. Higher voltages help improve performance, which also helps increase efficiency.
The charging infrastructure is seeing a lot more fast chargers. No one wants to wait a full day to charge their vehicle. As EVs become more prevalent, the need for fast chargers will increase.
We have shown that the grid capacity, and higher electricity demand, especially with electric vehicles will require an increase in the capacity as well as the stability of our electric grid.
How Can Silicon Carbide Help?
We talked about increasing the operating voltages. This is where Silicon Carbide (SiC) excels. Figure 7 shows some of the ways that SiC can help. It operates at voltages much higher than other technologies.
Figure 7: How can SiC Help?
This might help reduce the number of switching devices needed and it might help increase the efficiency.
SiC operates at a higher switching frequency, which reduces the overall size of a system by decreasing the size of the passive components such as magnetics and capacitors.
With these improvements, we have lower semiconductor losses which reduces the wasted energy that we saw before and helps combat the rising cost of energy.
Solid State Transformer Example
Currently, when we try to change the voltage or increase the voltage of an AC system, we use a low-frequency transformer that is very large, very expensive and not very efficient compared to other methods.
In this example, we see a solid-state transformer in Figure 8, which means that we're using semiconductor devices and operating them at much higher frequencies to lower the magnetics, which also reduces the size of the passives to increase the overall system efficiency.
Figure 8: Solid State Transformer
These devices, however, don't have the same voltage rating as grid voltage (65 kV or 100 kV).
What we do is add a bunch of cells in series which allows the voltage across each cell to be reduced while being connected to a very high voltage.
Now these cells consist of what we call half bridges, which are two MOSFETs in series.
In this case, we take an AC voltage and convert it to DC. The DC voltage is then switched to a very high frequency across a transformer to step-up or step-down that voltage, and then we reverse the process converting that switching voltage to DC and then converting it back to AC at a lower voltage.
So SiC, with its ability to operate at higher voltages, can reduce the number of cells in a solid-state transformer. It improves reliability, improves efficiency and lowers the overall cost of doing this work.
Modular Multi-level Converters
SiC MOSFETs are revolutionizing power electronics with their superior electrical properties compared to traditional silicon-based devices. Their higher voltage capabilities bring significant benefits to Modular Multilevel Converters (MMCs), shown in Figure 9.
Figure 9: MMC
Key Advantages:
Lower Cell Count:
- SiC MOSFETs can handle higher voltages, reducing the number of cells required to achieve the same overall voltage in an MMC. This simplification leads to a more compact and efficient design.
Fewer Semiconductor Devices:
- With higher voltage handling, each SiC MOSFET can replace multiple lower-voltage silicon devices. This reduction in the number of semiconductor devices simplifies the circuit and enhances reliability.
Fewer Gate Drivers:
- Each semiconductor device requires a gate driver. Fewer semiconductor devices mean fewer gate drivers are needed, which simplifies the control circuitry and reduces the overall system complexity.
Less Points of System Failure:
- A reduced number of components (cells, semiconductor devices, and gate drivers) translates to fewer potential points of failure. This enhances the overall reliability and robustness of the MMC.
Less Wasted Power:
- SiC MOSFETs have lower switching losses and higher efficiency compared to silicon devices. This results in less power wasted as heat, improving the overall energy efficiency of the MMC.
Lower Cost of Ownership:
- The combination of fewer components, higher efficiency and increased reliability leads to lower maintenance costs and longer system lifespans. This reduces the total cost of ownership over the system's operational life.
The adoption of SiC MOSFETs in MMCs offers substantial benefits, including reduced complexity, enhanced efficiency, and lower costs. These advantages make SiC MOSFETs a compelling choice for modern power conversion systems.
Half Bridge Cell Example
The bar graph in Figure 10 shows that for each half-bridge cell, if you're using 1.2 kV devices for a 35 kV input, you would need to have 870 of these half-bridge cells to support that 35 kV. You can see as we increase the voltage rating of these devices, the number of cells goes down. At 3.3 kV, which we have SiC for, it cuts that in more than half. If we have 10 kV devices then we would only need 60 of these cells instead of 870.
Figure 10: MMC
You can see the advantage of using high-voltage devices in high-voltage applications.