Today, we are in the early stages of a new era of power electronics that will shape the decades to come. Electric vehicles with battery-powered or hybrid engines are in high demand and will eventually replace gasoline and diesel vehicles. These vehicles draw energy from an AC grid connection, in which case an on-board charger charges the vehicle battery, or from a fast external DC charger that connects directly to the vehicle battery during charging. Since powering vehicles with electricity from coal-fired power stations does not make sense from an energy standpoint or from an environmental standpoint, the demand for solar and wind energy is growing rapidly, while energy storage systems are storing energy for future use Just in time. As a result, the market for electric vehicles, on-board chargers, electric vehicle charging stations, solar, wind and energy storage systems is growing rapidly.
An example of the rapid growth of the power electronics market
Another area of rapid growth in power electronics is components used in data centers, due to the increased use of cloud computing, artificial intelligence and online internet services. Uninterruptible power supplies provide reliable power to these data centers. Circuit boards in data center electronics contain many onboard power supplies that convert the main input voltage to 48 V and then to the lower voltages used to drive processors, FPGAs, and memory in the data center.
These new applications require high efficiency and high power density. In-vehicle EV chargers shouldn’t take up too much interior space. New developments in on-board chargers allow the same space but must deliver double the power. Solar inverters used in utility-scale solar farms are built using modular units that can be moved by two people. Increasing the power of the unit without adding weight is a major trend in solar inverters. Finally, in battery-powered vehicles, higher efficiency translates into longer range. Higher power density means lighter vehicles, which will also lead to longer driving ranges and greater flexibility in vehicle design.
In these applications, silicon power semiconductors are being replaced by silicon carbide and gallium nitride power switches. SiC and GaN are wide bandgap materials that allow power switches to operate at higher temperatures, higher frequencies and higher voltages than traditional silicon-based power switches such as IGBTs or silicon MOSFETs.
Although they are often mentioned together, there are some important differences between SiC and GaN that lead to different fields of use.
For a given R DS(on) and breakdown voltage, GaN devices have lower total capacitance compared to SiC devices. However, SiC has better thermal conductivity and flatter temperature coefficient compared to GaN, making SiC more popular for high power and high temperature applications. SiC has found its way in applications requiring 650 V or higher devices, while GaN has found its way in applications between 100 V and 650 V. GaN devices with rated breakdown voltages of around 100 V are used for medium voltage power conversion of 48 V down to lower voltages. This voltage range is suitable for cloud computing and telecom infrastructure with isolated bus converters. Additionally, AC/DC power supplies for cloud computing and USB PD applications will contain 650V GaN power switches, the correct voltage rating for AC/DC conversion, with a universal input voltage range of 90 VAC to 265 VAC. The high frequency of GaN allows the passive components of the power supply to be much smaller, resulting in an extremely compact overall solution.
Wide Bandgap Applications
In contrast, silicon carbide devices are designed for 650 V and higher. SiC is the best solution for various applications at 1,200 V and higher. In the long term, applications such as solar inverters, EV chargers, and industrial AC/DC conversion will all migrate to SiC.
The new markets mentioned earlier will drive new markets. There is a strong need for efficient power conversion of AC medium voltage grid voltages. Silicon carbide holds great promise in solid-state transformers, where current copper-magnetic transformers are replaced by semiconductors to improve efficiency, reduce harmonics, and enhance grid stability. The next revolution in power electronics has arrived. Up-and-coming SiC and GaN will help make the future of power electronics more efficient and compact for a variety of applications.