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Ousting 1900s-era Tech? Solid-state Circuit Breakers Extract DC from AC without Magnetics

July 06, 2021 by Kate Smith

Extracting DC from AC without any magnetics at all? A new solid-state circuit breaker put forth by Amber Solutions in partnership with Infineon Technologies stands to cause some pretty intense waves by displacing the nearly century-old technology upon which our electrical infrastructure is built.

Is it possible to extract DC from AC without the use of magnetics of any kind? 

All About Circuits had the chance to sit down (digitally) with Amber Solutions’ Founder and CEO Thar Casey and Infineon’s Senior Director of Switching Power Steve Bakos to talk about today's announcement from Amber about a solid-state circuit breaker that promises just that.

The conversation that followed ran the gamut from breaking down the extraordinary claim the two companies are making all the way down to the nature of the engineering mind when confronting new ideas and challenging old ones.

 

Extracting DC from AC—Without Magnetics Involved

The nature of the solid-state solution at hand is that it can side-step the wear and tear to which traditional mechanical solutions are subjected. What you worry about instead, says Casey, is whether the solid-state solution can handle the "hostile environment of electricity—from surges, inductive capacitance, overcurrent." These "hostile" elements don't only come from the grid side but also from the inductive load of the device being turned on.

"And now you've got this cute little semiconductor solution sitting out there inside a circuit breaker and saying, "Whoa, I'm getting zapped from both sides!" And it's going to blow up." But, he says, Amber's circuit breaker is able to protect the AC switch intelligently, by managing and controlling the sine wave of electricity accordingly.

The part that starts to raise eyebrows is the how. 

The "enabler" of this technology is the AC-to-DC conversion, which isn't really AC-to-DC conversion at all. "In reality," says Casey, "we do not convert power from AC to DC. In reality, we extract DC directly from AC main without any electrolytics, magnetics, transformers—without any rectifiers, without any of that stuff. It's in a solid-state tiny, tiny board."


 

Amber CEO and Founder Thar Casey with the solid-state circuit breaker. Image used courtesy of Amber Solutions

 

The role of the DC power extracted is to power the microcontroller on the board and the AC switch itself. This DC is also what powers the peripherals that Casey says will make these circuit breakers so smart: "This DC is also the source for other sensors, such as [those for] energy monitoring, metering, Wi-Fi, Bluetooth, air quality sensors, whatever."

"This is a magnetics-free AUX supply for the local microcontrollers and drivers and sensors," adds Bakos. “So it's a 2, 3, 4, maybe 5 W supply that sits locally in the module. And that's been the challenge when you put intelligence into these AC circuits and things: you have to generate a local 3 V, 5 V, maybe 2.5 V supply for the microcontrollers and control elements. And, obviously in the past, traditionally, you'd stick a transformer on there or an extra winding and some capacitors, etc., and that stuff takes up space."

This concept of saving space is an important one in the home applications Amber and Infineon are targeting, where Casey points out that "Sometimes a fraction of one centimeter is the difference between owning the market share and not owning the market share because the electrician's going to have a problem installing it."

 

Amber Solid-state AC Switch. Image from CES

 

“Validate It with Steak” 

The “how” of Amber’s innovation works is held understandably close to its chest.

So how do you convince people you’re changing the world if you can’t explain the details?

Especially when contemplating potentially industry-shaking innovations, engineers often bemoan this unfortunate intersection of innovation and corporate secrecy. But, Casey says, this is not a case of “all sizzle and no steak.” 

“Validate it with steak!” he says. 

For their work, Amber was recognized with a CES 2021 Innovation Award (and security was tight in their suite at CES 2020 for fear that someone could pocket one of their devices and make off with it into the Las Vegas winter).

As votes of confidence go, it’s also a pretty promising prospect to have Infineon, one of the largest tech companies on the planet, in your corner. 

“There's big potential, untapped potential for us in terms of MOSFET switching,” says Bakos, mentioning the suite of Infineon technologies at the ready for use in conjunction with these intelligent switching applications, including PSoC controllers, drivers, security, and sensors. 

It's worth noting here that Casey anticipates a forthcoming demonstration of this form of circuit protection in the coming months, so stay tuned for that.

 

The Why: Faster Tripping, Smarter Tripping in Next-gen Homes

When people use the term “smart home,” there’s usually a connotation of a smart thermostat or smart blinds or some other form of device which with consumers can interact via a smartphone app. 

But Casey points out that the next generation of home technology can actually refer to technologies that individual consumers don’t necessarily interact with on a regular basis—namely circuit breakers.

“Now [consider] the house, which is the single largest investment for almost everyone out there. And they're still using early 1900s electromechanical technologies. It doesn't make sense.”

Bakos adds, “Another way to think about this is the electromechanical circuit breakers that we all know and love in our homes are built to survive catastrophic events. I think it's safe to say that the Amber solution is built to avoid catastrophic events.”

“From the time the electromechanical circuit breaker says, ‘I have to trip!’ to the time that it physically shuts off, there's an additional four cycles of electrical cycles. We trip 3,000 times faster than an electromechanical switch.” This process can take place, “in the fraction of the beginning of the first cycle.”

By quickly repeating a pattern of “sample-hold-test,” the circuit breaker can essentially wait and see whether an anomaly is arcing that requires tripping or merely the presence of a new device that it doesn’t yet recognize, such as a new garbage disposal. Casey calls this “nuisance tripping”: “It's going on right now massively in the industry, but nobody wants to talk about it as much. But, behind closed doors, they do talk about it because they're getting a lot of nuisance tripping.” 

He then explained the logic, if you will, that an anthropomorphized solid-state circuit breaker goes through: “That first signature comes in and it says, "Whoa, that looks like an arc! But, you know what? I have plenty of time to decide. Let me test it again. Oh, no, it adjusted itself. Now it’s a regular sine wave. It's not an arc. Let it go.’” Now, if it sees a repeat of that same signature again, it will recognize it as an instance of arc and shut off the electricity.”

This sounds like a lot of “thinking” to fit into a very short amount of time. But, Casey says, “We're still faster than electromechanical.” 

 

Adoption (AKA “In with the Old, in with the New”)

When asked about the differences between placing these new circuit breakers in new homes as compared to retrofitting them into old ones, Casey was quite clear that Amber’s mindset is to tackle both, with a somewhat surprising slant towards retrofitting, arguably the more difficult of the two:

“It's not about the new construction. Anybody and everybody can go after new construction. OK, sure, that's good. But that's not where the big, big, huge market is. The huge market is retrofit.” He went on to discuss that new construction and updates to homes give plenty of opportunity for new GFCI (ground fault circuit interrupter) smart outlets.  

 

Amber Smart GFCIs. Image from Amber Solutions

 

This focus on both new and retrofitted technology explains a lot of the mindset Amber has espoused regarding form factor: “…we didn't go after a brand new circuit breaker panel to accommodate our circuit breaker. No, we went after existing circuit breaker panels to remove one of their circuit breakers and put our circuit breaker in it.”

But, along with enthusiasm for the benefits of adoption, Casey also has something of a warning for those who fail to adopt quickly enough:

“At the end of the day, when you show something like this to the companies that we're engaging with, they recognize, look, the genie is out of the bottle. Either we're going to have to jump on that bandwagon or we could potentially be another company like Kodak or like Polaroid or like others, if you will, who blinked a little bit and the market just went right from underneath their feet overnight, unfortunately.”

“We believe that Amber is onto something and we want to be a part of it," says Bakos. "We believe that this solid-state switching for, say, residential applications and dimmer switches and circuit breakers—it’s going to happen. It's not ‘if.’ It's ‘when.’ And we're looking to collaborate with companies to help make it happen.”

 

Comparison of traditional power supplies, Amber's solid-state solution, and Amber's projected integrated chip. Image from Amber Solutions

 

Next up: From PCB to Single-chip Integration

The next big milestone for this technology is to turn this PCB-level solid-state circuit breaker into a single chip. Amber plans to continue the miniaturization of their AC-DC solution into a single chip package. The process technologies, however, for the power MOSFETs and the CMOS intelligence are significantly different. As noted by Bakos, “There's just no good way to practically integrate those two process technologies.”

This will drive them to either a multi-chip module (MCM) or system-in-package (SiP) solution. “We're looking for cost-effectiveness,” Bakos says. “We’re also looking for really good thermal characteristics.”

 


 

What's the future of power supply design based on your experience? What trends do you see changing the way power supplies are designed? Share your thoughts in the comments below.