Resettable high-voltage circuit protection for next-generation battery electric vehicles

Sponsored by Eaton

Battery electric vehicle (BEV) architectures continue to evolve. Higher charging rates, greater stored energy, bidirectional power flow and tighter packaging can increase the demands placed on high-voltage DC circuit protection.

Traditional protection architectures that coordinate contactors, fuses and pyrotechnic devices were developed for earlier BEV platforms. In some applications they remain effective, but higher fault energy, faster fault development and greater system complexity may reduce available design margin.

This article outlines how BEV fault behavior is changing, where conventional protection strategies may face increasing constraints and why some next-generation architectures may benefit from a more integrated and resettable approach.

Figure 1. Conventional xEV circuit protection architectures compared with Breaktor circuit protection technology.

BEV architectures are transferring higher energy at higher rates

Current BEV platforms differ significantly from earlier generations. Several trends are changing electrical architecture:

• Higher charge rates driven by fast-charging requirements
• More stored energy to support longer range
• More compact battery packaging that increases thermal and electrical density
• Bidirectional power flow (V2L, V2H and V2G) that expands fault scenarios
• Higher system voltages, including 400 V and 800 V platforms and beyond

Taken together, these trends increase the amount of energy transferred through compact systems. Protection and switching devices may therefore be required to operate under higher stress, shorter response windows and a broader range of high-voltage direct current (HVDC) fault conditions.

HVDC fault behavior is changing

HVDC faults are not new. What has changed is the context in which they occur. Higher stored energy, faster charging and denser packaging can allow faults to escalate more quickly. In some architectures, engineers must manage not only higher fault current, but also faster fault development, shorter decision windows and greater energy transfer in the first milliseconds of an event, including:

• Rapid fault-current rise
• Increased difficulty extinguishing DC arc energy
• Reduced time available for protection decisions
• Higher consequence of misclassification or delayed response

As system energy and charging power increase, some applications may need to consider short-circuit currents in the 20 kA to 30 kA range or higher. At the same time, normal fast-charging current may move closer to levels that reduce the margin between nominal operation and fault response.

This can narrow the operating window for protection devices.
In these conditions, devices may need to handle a wider range of operating and fault scenarios, including:

• Continuous high current during charging
• Rapid interruption of high fault current
• Predictable operation during transients, signal errors, communication loss and auxiliary failure

Figure 2. Higher stored energy, faster charging and denser packaging can allow faults to escalate more quickly.

Constraints in conventional protection architectures

Fuse and contactor architectures

Conventional BEV protection depends on sequential coordination:

1. Detection by the BMS and sensors
2. Switching via contactors
3. Protection via fuses

This model assumes enough time for detection, signaling and handoff between components. As operating current and charging power rise, that margin can shrink. Under these conditions, it may become increasingly difficult to maintain reliable sequencing across the entire range of expected scenarios, and several limitations become evident.

• Coordination gaps across detection, switching and interruption functions
• Contactors may not be optimized to interrupt high-energy DC faults on their own
• Potential for contact welding and degradation of isolation performance under severe fault conditions
• In some cases, fuse response may not align with faster fault dynamics
• Reduced design margin as system voltage, current and stored energy increase

These considerations do not necessarily indicate a design deficiency. In many cases, they reflect architectures operating closer to the limits assumed during earlier design cycles.

Figure 3. Fuses and contactors require reliable sequencing, which may become more difficult to maintain across the full range of expected conditions.

Pyrotechnic protection approaches

Pyrotechnic devices can address some fuse-coordination issues by forcing the circuit open. Depending on the implementation, they may also introduce a different set of constraints.

• Dependence on an external trigger: In many designs, operation depends on a trigger signal from another system
• One-shot operation: Following activation, service intervention and component replacement may be required
• Faster trigger requirements: Future battery systems may require response times measured in hundreds of microseconds, depending on architecture and fault scenario
• Additional BMS complexity and associated cost
• Potential for nuisance activation: If evaluation windows become very short or system inputs are ambiguous

As fault energy increases, designers may need to balance earlier intervention against the risk of acting on incomplete information.

Figure 4. Pyro fuses and contactors can address some fuse-coordination issues; however, the protection gap is increasing with faster charging demands.

Protection performance is increasingly architecture-dependent

In earlier EV platforms, circuit protection was largely a component-level choice. Engineers selected contactors, fuses or pyrotechnic devices by rating, then coordinated them with timing margins and external control logic. If baseline requirements were met, many combinations could be made to work. For some modern BEV architectures, that approach may no longer provide sufficient margin on its own.

Protection performance can depend on how detection, switching, interruption, communication and power availability interact under severe conditions. When those functions are not aligned by design, component ratings alone may not be enough to achieve the desired level of protection performance.

Circuit protection is increasingly determined by system architecture, not only by individual component ratings. The protection concept influences fault response, subsystem dependencies, recovery capability and vehicle availability.

A protection architecture intended for future BEV platforms should:

• Accommodate higher voltage, current and stored energy
• Integrate detection, switching and protection functions where appropriate
• Provide predictable response across the defined fault envelope
• Maintain safe operation with limited dependence on external trigger chains
• Minimize dependence on single-use protection elements where feasible
• Permit recovery after non-catastrophic events where appropriate

Integrated protection architectures

A different approach is emerging, one that integrates protection and switching into a single, self-contained device. Compared with architectures that coordinate separate contactors, fuses and pyrotechnic devices, integrated approaches eliminate coordination dependencies by design.

• Combine detection, interruption and isolation functions within one device
• Reduce dependence on BMS timing and external trigger chains in some implementations
• Respond autonomously to defined high-energy DC fault conditions
• Provide more consistent response across defined fault conditions in some application

Figure 5. By using electrodynamic forces during a fault, integrated devices like Breaktor can accelerate contact separation and help limit fault current. This reduces stress on downstream components and improves overall system robustness.

Figure 6. Integrated protection architectures combine detection, interruption and isolation in a single device to improve response consistency under high-energy HVDC fault conditions.

Resettable protection and serviceability

Many real-world fault events, like the following, are not catastrophic.

• Charging station failures
• Communication loss on auxiliary systems
• Transient overcurrent events
• Sensor misreads or misfires

With single-use protection approaches, these events can still lead to:

• Stranded vehicles
• Costly component replacement
• Battery pack swaps
• Unclear liability across vehicle, grid, and charging infrastructure

A resettable protection approach allows recovery from manageable events, support vehicle availability, and shift certain service actions to planned maintenance intervals. This can significantly reduce downtime and total cost of ownership

Figure 7. Resetable scenarios

Evaluation questions for engineering teams

As protection becomes more architecture-dependent, engineering teams should also reconsider how technologies and suppliers are evaluated. In practice, that means asking questions such as:

• Which fault scenarios exist across the entire ecosystem—vehicle, grid and charging infrastructure?
• How often will protection devices encounter these events in the real world?
• Which faults should permit recovery, and which should not?
• Is the protection function self-contained, or does it depend on external systems and timing?
• Can the technology scale with future BEV energy levels?
• Is system response predictable and repeatable?

Conclusion

BEV electrical systems are evolving in ways that challenge protection architectures developed for earlier platforms. As energy levels, charging power and system complexity increase, protection strategies may need to evolve as well.

Legacy approaches are facing increasing constraints, not because they are poorly designed, but because system assumptions are changing. In some applications, coordination gaps can widen, dependencies can increase and available reaction time can shrink.

Integrated, resettable protection technologies represent a shift from single-use components toward architecture-level safety functions. By simplifying certain aspects of fault response, reducing selected dependencies and enabling recovery in
defined scenarios, they provide a more sustainable foundation for next-generation electric vehicle platforms.

Products featuring Breaktor circuit protection

Battery disconnect unit

The Battery disconnect unit (BDU) is designed to efficiently distribute power throughout the EV system. With the integration of Breaktor, the BDU provides improved quality and simplified architecture by combining current switching and resettable bidirectional short-circuit protection with fast actuation (up to 900V).

Enabling reduction of up to 15 components from the BDU assembly, Breaktor’s integrated coil driver, economizer, and sensing/triggering circuit reduce overall cost and complexity. Additionally, it’s self-triggering design, diagnostic electronics, and mirror contact help to ensure utmost safety and reliability.

FLEX power distribution unit

The next generation high-voltage intelligent FLEX power distribution unit (FLEX PDU) monitors and manages all power distributed to power electronics and provides central protection for the electrical system for hybrid, fuel cell and fully battery electric commercial vehicles. Fully customizable to meet a commercial vehicle’s specific requirements, the FLEX PDU can be integrated with Breaktor. This allows for integrated over-current protection for high power loads including traction inverters and DC fast charge.

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Microchip’s PAC1761 and PAC1861 power monitors track accumulated energy in 48 V systems

Microchip Technology has introduced the PAC1761 and PAC1861 families of digital power monitors for 48 V power architectures. Besides reading instantaneous voltage and current, the devices accumulate power measurements over time, which Microchip says lets a system react to its energy use as it happens. The company lists automotive, AI/data center, server, networking, industrial, telecom/Power over Ethernet (PoE) and 48 V power distribution among the applications.

Both families measure bus voltages up to 65 V and carry 75 V of spike protection. Microchip says the headroom is there to ensure transient survivability. The PAC1761 is the 12-bit option and the PAC1861 the 16-bit option.

Each part is a single-channel, bidirectional monitor for high-side or low-side sensing. An external sense resistor sets the full-scale current, and the sense range is 100 mV full scale, configurable to 50 mV. Microchip cites 1% power measurement accuracy over a wide dynamic range, on-chip accumulation of 32-bit power results for energy measurement and a coulomb-counting mode in which the accumulator sums sense-voltage values. Coulomb counting is a common basis for estimating a battery’s state of charge. The digital interface supports SMBus 3.1 and I2C Fast Mode Plus at 1 Mbps, plus a 3.4 Mbps High Speed Mode.

Programmable alerts flag voltage, current and power excursions. Step-limit detection identifies sudden load changes, and configurable accumulated-energy thresholds let a system act on long-term power behavior as well as instantaneous readings.

The monitors come in VDFN-8, VDFN-10 and MSOP-10 packages, including automotive-orderable variants. Microchip says pin-compatible options let designers move between devices as requirements, availability, cost or performance change, and can shorten qualification cycles.

Development support includes the EV12R33A evaluation board, priced at $49, plus a Python command line interface (CLI) with library, a Linux driver and a generic C library with code examples for multiple microcontrollers.

Both families are available from Microchip and its distributors. Pricing starts at $0.56 each in 10,000-unit quantities for the PAC1761T-3E/E3 and PAC1861T-1E/3P, both in the MSOP-10 package.

“The industry conversation is shifting from measuring power at a single point in time to understanding and responding to energy behavior across an entire system and its lifecycle,” said Keith Pazul, Vice President of Microchip’s Mixed-Signal Linear Business Unit. “The PAC1761 and PAC1861 families are designed to help customers build better performing and more reliable 48V systems that can measure instantaneous conditions and understand energy consumption and availability over time.”

Source: Microchip Technology

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Diodes launches automotive field-plated Super Barrier Rectifiers rated from 2 A to 8 A

Diodes Incorporated has introduced a family of field-plated Super Barrier Rectifier (SBRFP) devices for automotive use, including parts rated at 2 A, 3 A and 8 A. Diodes says the parts are drop-in replacements for comparable Schottky and PN junction diodes, and that their low forward voltage and reverse leakage suit DC-DC converters, reverse-polarity protection circuits, battery charging systems, automotive LED lighting and transmission control systems.

Diodes says its patented field-plated rectifier technology, built on a metal oxide semiconductor (MOS) manufacturing process rather than the metal-semiconductor junction of a conventional Schottky rectifier, overcomes the limitations of both Schottky and PN junction diodes.

The 8 A SBRFP8A60P5Q has a maximum forward voltage of 0.55 V at 8 A. A rectifier’s conduction loss is the product of its forward voltage and current, so a lower drop means less heat to remove at higher currents.

The 2 A SBRFP2M60P1Q and 3 A SBRFP3M60SAFQ have maximum reverse leakage currents of 12 µA and 7 µA, respectively, at 25° C and a 60 V reverse voltage, according to their data sheets. Schottky leakage climbs steeply with temperature, and Diodes says the low leakage helps minimize the risk of thermal runaway under high-temperature operating conditions.

Avalanche energy ratings reach up to 145 mJ, depending on the device. The data sheet lists that rating for the SBRFP2M60P1Q at an avalanche current of 2 A. Diodes puts the family’s avalanche capability at five to 10 times that of conventional Schottky rectifiers, which the company says lets the parts withstand surge events, load dumps and other transients common in automotive electrical systems.

The SBRFP2M60P1Q comes in a PowerDI123 package, the SBRFP8A60P5Q in PowerDI5 and the SBRFP2M60SAFQ and SBRFP3M60SAFQ in SMAF. All four operate across a junction temperature range of -55° C to +175° C.

In 1,000-piece quantities, pricing is $0.08 for the SBRFP2M60P1Q, $0.11 for the SBRFP2M60SAFQ, $0.13 for the SBRFP3M60SAFQ and $0.26 for the SBRFP8A60P5Q.

Source: Diodes Incorporated

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Scania to supply Core 800 battery packs for Prinoth’s electric snow groomers

Scania has signed a long-term agreement to supply its Core 800 battery packs to Italian snow groomer maker Prinoth, part of the High Technology Industries (HTI) Group. The packs will power two fully electric groomers: the Husky E-Motion and the Leitwolf E-Motion.

The agreement turns an existing collaboration into a long-term partnership. Prinoth introduced the Husky E-Motion in 2022, and Scania describes it as the world’s first market-ready fully electric snow groomer. The Core 800 has powered it since 2023, and the machine has been deployed in markets including Norway, France, Italy, the UK and the US.

“At Prinoth, we have chosen to continue our collaboration with Scania because of the high quality of their battery systems, which we have tested in some of the most challenging environmental conditions,” said Roberto Pegoraro, Prinoth’s Head of R&D Snow Groomers.

The Leitwolf E-Motion carries Core 800 packs in both top and side orientations, and Scania says the packs are configured to meet higher energy and power requirements. Prinoth launched the model in April 2026 and says it runs for approximately five hours under real working conditions and fast-charges from 10 to 80% in around one hour.

The Core 800 is a lithium-ion pack with 97 kWh of installed energy and a nominal voltage of 691 V. The pack is modular, so systems can scale from 21 kWh up to 624 kWh. It has integrated liquid cooling and a proprietary battery management system.

Scania’s industrial battery systems are also used in mining, construction, agriculture and logistics vehicles, as well as in energy storage and airport ground support equipment.

“Snow groomers operate in very low temperatures and steep terrain, moving heavy volumes of snow. This requires batteries that can deliver high power, withstand cold climates, and handle vibrations,” said Elin Åkerström, Managing Director of Scania Industrial Batteries.

Source: Scania

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Siemens Canada to develop a digital twin of Rock Tech’s Red Rock lithium converter

Rock Tech Lithium has signed agreements with Siemens Canada covering the Red Rock Lithium Converter, the lithium conversion plant Rock Tech plans to build in Ontario with capacity for up to 32,000 tonnes per year of lithium carbonate equivalent. Siemens will develop a digital process twin of the plant and support Rock Tech’s project team on the converter’s definitive feasibility study (DFS).

Rock Tech describes the twin as a virtual, physics-based model of the plant’s processes, energy flows and material streams that lets the company test, optimize and validate design choices, efficiency, emissions and operational reliability before major capital is committed. The first step is a digital process twin built on results from the DFS. The company plans for the technology to cover the project’s entire lifecycle, from the feasibility study through engineering and construction to operations.

The agreements are the first implementation phase under a memorandum of understanding the two companies signed in March 2026. That memorandum covers development and integration of Siemens digital twin technology, as well as evaluation of additional Siemens solutions, services and engineering support. Rock Tech says the goal is to position the Red Rock Converter as a blueprint for future converters in Canada and allied markets. The parties will also evaluate applying the cooperation to future projects in other G7 countries.

In Canada, Rock Tech’s feedstock sources include its wholly owned Georgia Lake Project. In July 2026, the company secured an option to acquire the Victory project, a lithium exploration property in Northwestern Ontario.

For the DFS, Siemens Canada will provide support in process control, instrumentation and automation architecture. Rock Tech launched the study at the end of June 2026 and expects to finalize it by mid-December 2026.

Source: Rock Tech Lithium

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Neo Performance Materials starts commercial EV traction magnet production in Estonia

Neo Performance Materials’ permanent magnet plant in Estonia, opened in 2025, is in commercial production, and the first commercial volumes of rare earth sintered magnets have gone to a Tier 1 EV traction motor customer.

Three Tier 1 motor manufacturers have awarded Neo multiple magnet programs, including traction motor applications, and the company has delivered qualification samples for each. Neo calls traction motor magnets the most technically demanding category of permanent magnets. Neo shipped the plant’s first magnet samples to a traction motor customer in June 2025.

Traction rotors run their magnets hot and against high reverse fields, so the material has to resist irreversible demagnetization at temperature rather than simply deliver peak remanence on the bench. Qualifying a new plant for that duty means showing that magnetic properties, dimensional tolerance and coating adhesion repeat lot to lot, which is the work the sampling phase does before a production award.

Neo expects two to three programs to be producing commercially before the end of 2026, and further traction motor and accessory magnet programs are scheduled to launch later in 2026. Automotive magnet programs are usually awarded for the life of the vehicle platform they supply, so a single award carries several years of volume visibility.

Phase 1A of the facility has nameplate capacity of about 2,000 metric tonnes a year. Phase 1B would raise that to roughly 5,000 metric tonnes a year and is in design. Detailed engineering, equipment procurement, supply chain planning and facility layout are all under way.

Neo’s long-term plans include reaching 20,000 metric tonnes of annual production through continued global expansion, a figure the company estimates could account for 10% to 15% of the projected rare earth permanent magnet market outside China.

“We built this facility in under two years and have won multiple program awards from Tier 1 motor manufacturers,” said Rahim Suleman, Neo’s President and Chief Executive Officer.

Source: Neo Performance Materials

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OBE Power secures new equity investment to expand its North American EV charging network

US charging network operator OBE Power has secured a major new equity investment from North Sky Capital. The investment complements OBE Power’s existing credit facility with Gresham House.

OBE Power will use the new capital to accelerate its expansion of its North American EV charging network, with a focus on multifamily, hospitality, healthcare, commercial and other destination-based properties.

“OBE Power’s business model is focused on deploying, owning, operating and managing EV charging infrastructure for property owners and institutional partners, allowing hosts to provide EV charging solutions without making significant capital investments or assuming operational complexity,” the company explains.

“We are proud to welcome North Sky Capital as a strategic partner, given its deep understanding of the renewable energy and sustainable infrastructure sectors,” said Luis Paul, cofounder and Managing Director of OBE Power. “With this strategic investment, OBE Power has secured the capital foundation required to support its ambitious expansion goals over the next three to five years.”

“North Sky Capital has evaluated the EV charging sector for several years, and we believe OBE Power presents a compelling and well-structured expansion opportunity in the market,” said Adam Bernstein, Managing Director of North Sky Capital.

Source: OBE Power

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