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Three design freedoms with SiC technology

While the performance and potential of SiC technology are unquestionable, some designers may still be initially hesitant to make up their minds about using SiC technology for new projects.

Author: Milan Ivkovic

While the performance and potential of SiC technology are unquestionable, some designers may still be initially hesitant to make up their minds about using SiC technology for new projects.

No one likes gratuitous adventures. But like any other electronics design project, we first need to fully understand the requirements and potential of the solutions available. Designers will then discover that the freedom of design enabled by SiC reduces all known risks.

As SiC technology reaches more market segments, designers can realize some new freedoms that are exciting and worth exploring. These include simplifying circuit topologies, reducing system size, and increasing energy density.

Let’s start with some background: Compared to Si-IGBTs and Si-MOSFETs, SiC MOSFET power systems can significantly reduce system cost, increase power density, improve efficiency, and control operating temperature by reducing energy consumption. Designers are excited to learn more about the benefits of SiC.

Today, designers are turning to SiC-based technologies in order to remain competitive and reduce long-term system costs. There are many reasons for this, including:

・ Lower total cost of ownership: SiC-based designs, despite requiring upfront investment, are more energy efficient, smaller in system size, and higher in reliability, resulting in significant system cost reductions.
Solve design challenges: Due to the properties of SiC, designers can develop devices that can shrink in size, operate at lower temperatures, and increase switching speeds while withstanding higher operating voltages.
・Increased reliability and improved performance: By reducing equipment size and operating temperatures, designers gain greater freedom to explore more innovative design options and easily meet market demands.

Next, we will discuss some key design freedoms in detail. .

Simple, efficient topology

SiC supports simple topologies that help designers do their jobs efficiently and meet the growing demand for efficient power-intensive DC/DC and inverters.

SiC can replace the three-level topology with a two-level topology, which reduces the difficulty of parameter control, takes up less space, and releases less heat.

In a power factor correction (PFC) stage hard-switching topology, a simple boost (using SiC diodes) and totem pole configuration can reduce SiC recovery losses. Achieving the same efficiency with Si-MOSFETs requires more complex topologies and digital control.

SiC can be combined with Si in multilevel topologies to improve price/performance. The following is an example of an improved three-level active neutral point clamp (ANPC) topology for a solar or energy storage Inverter:

System size reduction

Designers are constantly under pressure to do more in less space. Thankfully, SiC designs are smaller, lighter, and can support more efficient inverters and storage systems.

Servo drives are an excellent example. Servo motors used for object positioning need to respond quickly in order to increase the speed of operation. Therefore, the dynamic performance of the servo system can be improved by increasing the pulse width modulation (PWM) frequency. This necessitates the use of fast IGBTs or SiC as switches for the inverter stage of the servo drive.

Using SiC, designers can design smaller drivers, many of which do not require active cooling. With this freedom, designers can mount the driver directly on the motor. Additionally, designers can connect the DC bus directly to the motor, significantly reducing electromagnetic noise.

Enhanced energy storage function

Today, energy consumers are also becoming active electricity producers. SiC supports bidirectional power flow, enabling this transition.

For decades, energy storage has been an integral part of the process of generating, transmitting, distributing and consuming electricity. At present, the field of renewable energy power generation is developing rapidly, and more reliable power transmission is required to ensure that power is delivered to the corresponding location on time.

Energy storage systems offer a range of technological approaches that can be used to manage energy supply and demand, create a flexible energy infrastructure, and help utilities and consumers save costs.

In the fields of electric vehicle (EV) and solar charging, we are seeing strong benefits of bidirectional power flow enabled by SiC. For example, users of electric vehicles and solar systems can sell some of their electricity to utility companies when they are fully charged. Some SiC topologies can enable better bidirectional flow, improving energy storage systems.

The figure below shows the power density comparison of SiC and Si in solar inverters.

Main advantage: Power density increase from Si ➝ Si / SiC

Datasheet:

・ Si inverter 75kW
・ Si/SiC inverter 150 kW

Advantage:

・ Significantly improved power density
・Cost reduction in cooling and weight

Features:

・ 6 x IFX Easy2B ANPC modules
・ 26 x IFX EiceDrivers 1ED-F2

Conclusion: Advantages of SiC over Si

Energy loss reduced by 50%
10x smaller system size
100 times higher operating frequency
Quick switch function
high voltage operation