The Blog

Battery Management System Scalability

in Battery Management System

 

When designing Centurion BMS™, Nuvation’s fourth-generation battery management system and first off-the-shelf BMS, our goal was to create a set of modules that could be connected to the battery pack in different configurations to support a wide range of battery topologies with different chemistries, voltages, and capacities. Our industry research and consultations with customers revealed three main market verticals where such a configurable BMS was of greatest interest to manufacturers:

  • Specialty Vehicles – Battery powered traction systems and subsystems
  • Telecom Power Backup – Data centers and telecom towers
  • Grid Energy Storage – Micro grid, solar, wind, etc.

While not every target battery deployment we encounter fits neatly into one of these categories, this matrix enables one to evaluate the Centurion BMS in terms of its suitability to meet the full range of its target battery topologies.

A battery pack is typically scaled in one or both of two directions: vertically and horizontally. Scaling vertically involves stacking battery cells in series to increase pack voltage. Scaling horizontally involves connecting multiple stacks of cells in parallel to create greater capacity at the same pack voltage. Very large systems usually require the pack to scale both vertically and horizontally to deliver high voltage and high capacity.

Scalability Table 1

Returning to our matrix of battery pack configurations, we can summarize typical scalability needs as follows:

Scalability table 2

Centurion BMS has been partitioned into three distinct modules that are used as the building blocks of complete system.

  • Stack Controller – performs all processing required to manage a single stack of cells.
  • Cell Interface – provides the electrical interface to a group of 12-16 battery cells.
  • Power Interface – powers the BMS, measures high voltages and large currents, and provides the electrical interface to high-current switching devices.
3 BMS modules on a DIN rail

Centurion BMS has been partitioned into three distinct modules that are used as building blocks for a complete system.

5 BMS modules on a DIN rail

A typical large-scale battery is managed by one Power Interface, one Stack controller per battery stack, and Cell Interfaces (CI) each connected to as many as 12-16 battery cells per CI.

 

Separating functionality into these distinct modules allows Centurion BMS to scale to support a wide range of topologies. Multiple Cell Interfaces are connected together in a daisy-chain that increases in height as pack voltage increases. This daisy-chain is connected to a single Stack Controller that manages all cells in the chain. Multiple Stack Controllers can be connected together to support large packs with many stacks in parallel. The Power Interface isolates high-voltage and high-current components of the stack physically and electrically from the other modules. It can also power the BMS directly from the battery stack, eliminating the need for any external power supplies.

BMS Block diagram

BMS Block Diagram. Click to Enlarge

Centurion BMS is available in multiple variants that support a wide range of stack voltages. In future posts we will examine in more detail how we can use these three modules in various configurations to meet the voltage and capacity requirements of different pack topologies.

Visit Nuvation at the Battery Show

in Battery Management System

Battery Show banner
Nuvation Engineering will be launching our new  off-the-shelf Battery Management System at The Battery Show in the Suburban Collection Showplace in Novi, Michigan Sept. 16-18, 2014.

  • Visit us in booth #  B1621 on the show floor to see our new off-the-shelf BMS product demonstration in action. Linear Technology will also be showcasing their products using Nuvation’ BMS in their own booth, # E905
  • On Wednesday September 17, 3:00pm-3:45pm, in booth B1853 on the exhibition floor, Nuvation Engineering, Bloomy, and Linear Technology will be participating in a panel discussion about the future of battery management systems with respect to large-scale battery technologies. This panel discussion is free to all Battery Show attendees, and will offer expert insights into this rapidly growing area of battery technology.
  • September 18, 1:30-3:15, Conference Track 2, Ruby Ballroom – Battery Management Systems – Michael Worry, Nuvation’s CEO, will be participating in this conference track and discussing “Real-world challenges for battery management systems.

For more details, please visit our website Events Page.

Engineering Scholarship Winner

in Robots, Scholarship

Congratulations to Marina Dimitrov from Portland Oregon, the 2014 winner of Nuvation’s $1,000 engineering scholarship. Applicants were asked to submit a short essay about something they really enjoyed about engineering. Marina told us all about her work on robots that make elephants exercise!

Check out Marina’s winning essay.

Packy the Elephant Meet “Packy,” one of Marina’s oldest customers. Robot feeder and worktable Packy’s robot personal trainer is getting some upgrades from Marina’s FIRST Robotics team. Marina gets ready to make a robot!

Now a Sophomore at Stanford University majoring in Biomechanical Engineering, Marina discovered her passion for robotics during high school in the FIRST Robotics Competition, where she created robots that play Frisbee, soccer, and basketball (this time the robots did the exercising!).

Marina cutting metal Marina working in the lab. Elephant Feeder Process Flow Chart Elephant feeder UI flow chart. Robot playing sports Robots playing, ummm, what sport is that?

This summer she studied the “biomechanics of tuna” and is thinking of ways to make robots swim better by “striving to understand and mimic what nature has had millions of years to design.” Not a bad resume for eighteen years old – wait a minute, are we saying “Marina” is studying the biomechanics of fish at Stanford Hopkins Marine Station…I get the feeling we will be hearing more about this dynamic future engineer in the…future. Congratulations again Marina, and please drop by Nuvation’s California office sometime, and see if you have any biomechanical engineering tips for our air hockey playing robot.

Franken-Systems and Electronic Design

in Electronic Design Services

At Nuvation we began using the term “Franken-systems” many years ago (maybe back in the late 90’s?); nobody recalls the exact moment in time. Somebody probably blurted it out on seeing a lab setup with wires running all over between development boards and perfboard circuit prototypes. We’ve certainly seen the term other places as well, so we don’t know if we came up with it first. Doubtful we did, but we do like the term, it’s a concept that customers, vendors, and new colleagues all seem to understand.

A Franken-system refers to a collection of development boards for processors, FPGAs, sensors, and the like wired together to create a very non-form-factor early prototype in order to facilitate software and logic development. Sometimes we’ll make lab prototypes for certain circuits, sometimes we’ll have custom cables made, and sometimes we’ll go so far as to fabricate interposer cards to connect boards that have complicated interfaces, lots of connections or high-speed considerations.

A video Franken-system with 3 cameras.
Click to Enlarge

Some Franken-systems are “quick and dirty” while others can look quite well put together – the latter usually being mounted on a surface of some kind and often covered with polycarbonate to avoid inadvertent hands. There’s certainly a range to these setups, but they all have a common theme – enabling on-device software and logic testing before first full prototypes are available.

A Franken-system can be assembled and put into a developer’s hands in mere days, compared with weeks or months it may take before the full prototype is available, providing a setup on which to begin testing code and logic before actual hardware is developed. Simulators and virtualization can do great things and be very helpful, but ultimately until you’re working on the actual target chip, you’re always at the mercy of how well the simulator emulated it. This is particularly important for processors and hardened IP blocks in FPGAs. When you’re running on that development board you’re learning a lot about the processor – how the programming flow works, how the debugger interface works, how the boot loader works, how the I/O multiplexing works, and so on. Chip flaws will be exposed. Library limitations will be found earlier, and in general you’re efficiently de-risking your project.

A Franken-system mounted on polycarbonate to keep it together.

Looking beyond the processor itself is where you get into even more important results. On a good Franken-system your development board will now be interfaced to as many of the other target chips, devices and software as the hardware and software team can put together. Image sensors, ADCs, DACs, sensors, memories, transceivers, etc. – the more of these things that you can get into your

Franken-system the better. The upside rapidly outstrips the time and effort required to create even an elaborate Franken-system. Timing issues, driver problems, datasheet errors, register problems, subtle limitations – these things all can come up much earlier in the project process.

While the software/logic team works with the Franken-system they need to be ever-vigilant for the “discovered problems” that will impact the actual hardware design taking place in parallel. This is where one of the most profound upsides comes in; even a single somewhat-serious issue found through testing on the Franken-system, which allows for that issue to be resolved before the hardware prototype design is complete, pays for this activity. For example, imagine a chip-bug found in a transceiver that if unresolved would have required a prototype re-spin. And it doesn’t have to be a bug in the chip – a more common scenario is finding a subtle limitation in how a new device can be used that often only shows up in actual testing – on the Franken-system. Avoiding that re-spin saves you days or weeks of effort, and likely weeks of schedule, on top of the expense of a re-spin. That’s why Franken-systems are a key part of Nuvation’s First-Time-Right hardware design methodology.

Of course there are limits to the Franken-system approach. For example, you won’t be able to create a setup for some parts of the hardware design. For some parts you can’t get access to a development board (that issue can even apply to the main processor or FPGA, which should encourage you to look for a different processor), for some parts the wiring is impractical or too high-speed, and sometimes the processor/FPGA variant you’re using might not even have a development board in existence. These limits are drastically outweighed by the benefits, however, and are not sufficient reasons to forego the advantages.

Nuvation In the News – Autonomous Vehicles Research

in Autonomous Vehicles

Electronic Design News has published a story about Nuvation’s collaboration with the University of Waterloo on autonomous vehicles research. EDN began taking an interest in our exploration of this exciting emerging technology when our CEO Michael Worry suggested during a presentation at the 2014 EE Live! trade show in California that that it should be illegal for humans to drive.

Car Crash Image

Should it be illegal for humans to drive?

 

Autonomous Vehicle Research Presented at IEEE

Steven Waslander, the lead University of Waterloo researcher on the project, presented two Nuvation-sponsored research papers on promising autonomous vehicle technologies at the IEEE Intelligent Vehicles Symposium last June in Michigan. “Pneumatic Trail Based Slip Angle Observer with Dugoff Tire Model” explores ways autonomous vehicles can ensure accurate vehicle control “at the limits of tire performance,” and “MPC Based Collaborative Adaptive Cruise Control with Rear End Collision Avoidance,” well, that one’s a bit more self-explanatory when you know that “MPC” stands for “model predictive control.” Read More

New Battery Management System for Energy Storage Platforms

in Battery Management System

A couple of weeks ago Nuvation’s product management team asked me to start preparing some marketing materials for our new “gen 4” battery management system (BMS). Finally, it’s time to start talking about it! It’s been a while since we released a new “ready-to-ship” product, and we already have interested clients asking for more information. This is a true COTS battery management system – and it’s chemistry-agnostic, scalable, and configurable.

The new BMS is designed with a modular architecture (there are different physical BMS modules you can put together in a custom configuration for your target system) that makes it scalable for uses ranging from large electricity grid energy storage systems, large datacom/telecom systems like cell towers, and industrial transportation platforms such as tow motors, naval vessels, and mobile robots. We addressed safety by creating a fault tolerant fail-safe design with built in redundancy, and choosing processors with strong noise immunity.

BMS User Interface - Pack View

BMS User Interface – Pack View

But for me, the coolest part of this battery management system is it includes a Wi-Fi module, and we made an iPad app for it, so you can monitor the battery’s state of charge and other data remotely, on your iPad!

That’s all I can say for now (oops, did I accidentally leak a new impending product launch? Companies never do that, except by accident!). Stay tuned for more updates as we ramp up for a product demonstration at The Battery Show in Novi, Michigan this September.

Audio Testing…With a Pressure Cooker?

in Electronic Design Services

Nuvation recently developed a product for a client that was a high-quality audio recording device with an integrated microphone. Our client needed their device to have a high dynamic range and low noise, but also a low production cost. During the design phase we used engineering best practices to maximize the dynamic range and minimize the noise, and we selected the most cost-effective components that would meet the client’s product requirements.

anechoic_chamber

An anechoic chamber

 

 

We could get a ballpark estimate of a the system’s performance  using datasheet specifications and engineering analysis, but to accurately assess whether the design met dynamic range and noise specifications required complete system testing. This type of testing can be performed in an anechoic chamber, but for this situation renting and transporting all the equipment was cost prohibitive and too time-consuming. Read More

SoC FGPA Design Webinar with Nuvation, Altera, and ARM

in FPGA Design Services, News

Nuvation Altera SoC

SoC FPGAs enable engineers to take advantage of the flexibility of FPGAs while leveraging 3rd party IP cores, reducing component power consumption, and simplifying engineering requirements. The design flow of an SoC FPGA can reduce engineering efforts by as much as 30% calendar time and 35% engineering cost compared to standalone FPGA and FPGA/MCU configurations.

Allan Dubeau, Principal Design Engineer at Nuvation will be delivering a webinar with experts from Altera and ARM, comparing the design flow of an SoC FPGA to that of a traditional FPGA.

Join us on Thursday May 8 at 11am Pacific Time / 2pm Eastern Time for this inside look into how SoC FPGA architecture can reduce both design and product costs.

Learn More

Great Week at EELive!

in News

Michael-Worry_EELiveLast week we attended EE Live with our design partner Atmel, as part of the Atmel Tech on Tour series. Nuvation CEO Michael worry gave presentations on autonomous vehicle technology advancements, as well as the importance of battery management systems. EDN wrote a great article about Nuvation and Michael’s talks here.

If you missed it, you’ll be able to catch another live demo of the Nuvation battery management system at The Battery Show in September. Check out our News page for more details.