Why modernizing semiconductor breakers in the U.S. power grid is critical to the energy transition

Over the past few years, with growing concerns about the state of our environment, the transition to green energy has become a major focus. As a result, billions in investment capital are being poured into renewable energy solutions such as solar and wind power.

Meanwhile, the foundational technologies that will make the energy transition a reality remain the unsung heroes of this transformation. For example, the basic circuit breaker has not undergone significant design changes from the end of the 19thvol agewhen Thomas Edison developed them.

In recent years, it has become clear that modernizing circuit breakers in the national power grid will be crucial to the energy transition.

Problems with modernizing aging energy infrastructure

In fact, most of the US power grid was built in the 1960s and 1970s. In fact, more than 70% of the network is over 25 years old, making it particularly vulnerable to severe weather and other hazards. That’s why we’re seeing more and more frequent power outages lasts longer than in previous decades.

The transition to renewable energy further complicates matters due to the intermittent nature of these energy sources. Whenever the sky is cloudy for an extended period of time, solar panels do not produce any energy, and the same goes for wind turbines during extremely calm weather.

On the other hand, renewable sources like solar and wind can produce much more energy than usual on other days when the sun is especially bright or the wind is blowing especially hard at the turbines. As a result, renewable energy sources can create sudden jumps which cause frequency and voltage control problems in the system, exacerbating problems with the aging grid.

Conventional circuit breakers are not up to the task of transforming the power grid

In such situations, it is necessary to modernize the circuit breakers in the power grid. Circuit breakers must protect against overvoltages and short circuits caused by unexpected events such as lightning strikes, equipment failures, and more. They must also isolate any faults as quickly as possible to prevent damage from cascading throughout the system.

Unfortunately, conventional circuit breakers present several problems due to the physical limitations of their design. Because they are mechanical breakers, conventional circuit breakers are currently too slow to close circuits when such problems occur, resulting in high short-circuit currents and arcing that cause additional wear on the breaker contacts.

DC systems such as wind, solar, and energy storage are susceptible to particularly high current rise times, requiring response times within one microsecond. Therefore, bidirectional capabilities are also required to support the flow of current both into and out of the power grid. While newer semiconductor technologies do solve the switching speed problem, they do so at a significant cost – wasting electricity.

Of course, the main purpose of breakers is to open quickly in the event of a problem, so most of the time they are closed, allowing constant current flow. When closed, circuit breakers continuously conduct current, so minimizing conduction losses is crucial to reducing energy loss – especially when it comes to energy efficiency, which is the primary focus of the energy transition.

Solid-state switches switch much faster than traditional mechanical switches, but at the cost of higher conduction losses, resulting in significant energy loss that must be dissipated as heat. Therefore, eliminating this heat increases the cost, weight, and complexity of solid-state switches that use conventional solid-state switches.

Problem with IGBT switches

Solid-state circuit breakers (SSCBs) use power semiconductors instead of mechanical contacts to quickly open a circuit without any moving parts. Because semiconductors can open a circuit in just microseconds, they also dramatically reduce the amount of energy that can damage a system.

At SSCB, we have seen improvements in the semiconductors used to power switching. Until now, the type of power semiconductor switches commonly used in SSCBs used in AC and DC networks was the insulated gate bipolar transistor (IGBT). Unfortunately, IGBTs experience significant conduction losses compared to mechanical contact switches. The result is a voltage drop of approximately 1.75 V per IGBT, increasing to 2.75 V with the addition of a series diode in traditional IGBT circuits.

In fact, a standard SSCB implementation involves several IGBT switches connected in series, which raises the total voltage drop by 2.75 V each time a switch is added to the circuit. Multiplying the current by the total voltage drop reveals the amount of power lost in such circuits.

Considering that networking applications require hundreds of amps, using IGBT switches wastes hundreds of watts of power. This translates into significant amounts of wasted energy combined with the addition of expensive thermal management systems to deal with all the heat produced by the lost energy.

The best of both worlds

However, Ideal Power’s bidirectional B-TRAN switch solves the problems caused by IGBT switches, and as a result, SSCBs offer the best of both worlds: ultra-fast switching and extremely low conduction losses. The switch resembles a symmetrical bipolar junction transistor with two control base connections, allowing conduction in both directions.

So far, studies show that B-TRAN has faster turn-off time than IGBT switches with a voltage drop of just 0.6 V at 50 A, resulting in a voltage drop four times lower than that of bidirectional IGBT SSCB. From a practical point of view, B-TRAN dissipates only 360 watts compared to over 1500 watts dissipated by a bidirectional IGBT based circuit in a 12 kV 50 A SSCB.

Additionally, due to its bidirectional design, a single B-TRAN device replaces four devices (two IGBTs and two diodes) in a conventional AC or DC circuit breaker. Using fewer components typically means smaller systems, greater reliability, and reduced costs at the system level.

Therefore, SSCBs equipped with B-TRAN switches are ideal for mass-scale applications such as power grids and renewable energy solutions.