making wireless electricity a reality, faster

Making wireless electricity a reality, faster

Andre Kurs

Founder

WiTricity Corporation

[email protected]

About WiTricity

COMSOL Conference 2014 Boston 2

• Developing wireless electricity over distance for a wide range of applications.

• MIT spinoff founded in October 2007.

• COMSOL users since our days in academia.

• Headquarters in Watertown, MA. Additional R&D office in Nibley, UT.

The original MIT team

Highly Resonant Wireless Power Transfer


Highly Resonant Wireless Power

Transfer

ResonanceStrong response at resonant

frequency

Magnetic Resonance

Energy oscillating between magnetic (B) and electric

fields (E)

Coupled Resonators

Efficient and selective energy transfer with coupling that mediates energy exchange

between resonators

• If the quality factor Q of the resonators is high enough (highly resonant), efficient power transfer can be achieved over distances a few times the size of the resonators.

• This condition can be difficult to achieve, so adequate electromagnetic design is crucial.

Consumer electronics applications


Wireless charging of mobile devices

(through surfaces)

Wireless rechargeable batteries

(charge inside the device)

Wireless charging of laptops and peripherals

(multiple devices)

Automotive applications


Wireless charging of electric vehicles and hybrid

electric vehicles

Medical applications


Implantable devices: LVADs and CRMs, ophthalmic and cochlear implants, surgical and handheld devices, mobile equipment carts

Sample resonators


WiTricity’s resonators typically consist of:• At least one winding made of good electrical conductor.And may also contain:• Magnetic material (such as ferrite) to redirect the magnetic field.• Metallic surfaces for electromagnetic shielding.

Original MIT demonstration(self-resonant helix)

Shielded flat resonator (smartphone)

Copper winding

Flattened solenoidal resonator(automotive, industrial)

Ferrite block

Metallic shields

Bringing highly resonant wireless power to market


• WiTricity works with licensees to reduce time-to-market of their solutions.

• Different levels of engagement possible: from technology transfer to full-fledged custom designs.

• WiTricity created WiCAD to accelerate product development and validation.

• WiCAD is now offered to licensees who want to explore new applications and designs.

Licensing model• Can’t possibly tackle all applications by

ourselves!

• Plays to our strengths as an R&D-focused company.

What is WiCAD?


• Special purpose software tailored to the development of wireless power transfer systems from concept to prototype.

• Includes electromagnetic (through COMSOL), impedance matching, and circuit design capabilities. Predicts compliance with human safety and emissions standards.

• Scalable client/server architecture.

• Used by WiTricity’s internal technical staff as well as by our licensees.“We eat our own dog food.”

Why we chose COMSOL back in 2007


• Originally used to support our academic work.

• Most natural fit for the work we needed to do initially. COMSOL’s flexibility allowed for greater freedom in R&D. Powerful MATLAB® integration and scripting capability.

A. Karalis et al., Annals of Physics 323 (2008) 34A. Kurs, M.S. Thesis, MIT (2007)

MATLAB® is a registered trademark of The MathWorks, Inc.

Using COMSOL to drive innovation


• From the beginning, finite-element modeling has played a key role in WiTricity’s R&D.

• Powerful features such as direct access to weak form equations let us quickly implement unsupported features and try far-out ideas to figure out what works.

Experimenting with resonator designs Optimization of high-frequency conductors

(DC resistance)/(DC resistance)

Developing prototypes and validating results


Electromagnetic coupling vs. position Quality factor vs. frequency

• Applying results and techniques from R&D to prototype development.

• Whenever possible, test predictions against measured data.

• Refine model and add complexity when necessary.

Feed back into R&D

Human safety and EMI compliance


Specific Absorption Rate, dB relative to FCC limit

• Direct access to COMSOL’s solution data allowed us to compute local averages (for human safety) and generalized far-field emissions (for electromagnetic interference).

• Good agreement with available lab data.

Far-field emissions

Critical to know that our technology meets safety standards in a particular application!

“WiCAD 0.1”


Productivity wins• Code can be easily combined with other MATLAB functions and scripts.

• Automated most common tasks so experienced users could spend more time doing R&D.

• New users with MATLAB experience get up to speed in a few hours.

Object-oriented MATLAB code interfacing with COMSOL 3.x, accessible through a command line interface.

Limitations• Some familiarity with MATLAB necessary.

• Requires a COMSOL and MATLAB installation for each user, no matter how infrequent (doesn’t scale).

• Lack of instant visual feedback.

“WiCAD 0.1” establishes a new dynamic


WiCAD 0.1

Applications and

Prototyping Team

R&D Team

Drive innovation

Model refinement

New features/fixes

Virtual prototyping

Feature requests/suggestions/bug reports

• Sharing a common codebase reinforces positive feedback loop between R&D and applications teams.

• Each team can focus on its core strengths.

• Computational models and software improve constantly.

• Lays down basic software development principles and a solid foundation for future scaling.

2010: COMSOL’s Java API is introduced


Downside (for us)• Much of our existing MATLAB code soon to become obsolete

Upsides• New API is more powerful and flexible.

• Relatively straightforward to port and extend the functionality of 3.x codebase to the new API.

• New code is much cleaner, adheres to recommended practices for Java programming (object-oriented design, pervasive unit testing, proper documentation).

Already ahead of where we started!

• Possibility to work directly in Java and take advantage of countless Java libraries.

Adding a GUI and cluster support


WiTricity user

Local Network

WiTricity cluster running COMSOL

• Used Java’s numerical analysis, 3D rendering, and GUI layout libraries to develop an accessible client application.

• Client is available to all WiTricity employees.

• Acquired a computer cluster running COMSOL.

• Wrote a cluster-side application that handles requests from the client application, translates them into COMSOL cluster jobs, and sends the results back the client.

End resultWiCAD: a software tool that anyone within WiTricity can use to design a wireless power transfer system. It takes literally minutes to get started.

Rolling out WiCAD to our partners


InternetCustomer

Client

WiTricity Hosted Servers

Backend DB(Data and User Management)

HTTPS

• Significant changes on top of internal client/server setup to allow our partners to use WiCAD remotely.

• Redesigned the client application to steer users towards better designs Harder to commit mistakes than with internal client application, but less flexibility. Additional functionality should gradually be made available to our partners.

• Implemented a custom job scheduler to ensure all users get a fair share of cluster time.

• Client and server communication designed and architected with system security in mind: Secure communication between client and server Third party security audit for architecture and performance

Anatomy of wireless power transfer system


Transmitter Resonator

Receiver Resonator

DCSupply

Matching NetworkInverter

DC Load

7

Rectifier/RegulatorMatching Network

Resonator Design(Electromagnetics)

FEM models (COMSOL)

Circuit Design(Electronics)

WiTricity models

AC

AC

Design steps

1. Resonator design2. System design

• Safety and emissions check3. Fine-tuning

Step 1: Resonator design


• WiCAD comes with a library of commonly used resonator types, including many of WiTricity’s reference systems.

• Users are free to modify existing designs, or create their own from scratch.

• Easy to set up parametric sweeps.

• Supports multi-resonator applications (one transmitter to many receivers).

• Once user presses the “Calculate” button, the study is sent to COMSOL on the cluster. While computation is ongoing, user is free to: Work on other aspects of the same

study. Work on a different study altogether.

Step 2: System design


• Uses either COMSOL solutions or measured data as starting points.

• Determines optimal power delivery and end-to-end efficiency.

• Can be used to design applications from milliwatts to kilowatts.

• Shows voltage and current stresses on electronic components.

Step 2: Safety and Emissions


• Check whether system as designed is likely to comply with regulations on:

• Far-field emissions (radio interference).

• Human safety.

• Instantly see impact of electronics design changes on compliance. No need to solve FEM problem again.

Step 3: Fine-tuning


• Properties of physical prototype may differ somewhat from those predicted by WiCAD.

• The fine-tuning step lets user input measured values and adjust the system accordingly.

• Can also perform sensitivity analysis due to component tolerances.

Looking ahead


• WiCAD empowers users to create highly resonant wireless power transfer systems from conceptualization to lab prototype.

• It only takes minutes to get up and running with WiCAD!

• It is an important part of our strategy for reducing R&D cycles and time-to-market of products.

• Built to scale.

• As the user base grows, we look forward to adding more features and further refining our models based on feedback.

• COMSOL’s new Application Builder should allow for much easier development of tools similar to WiCAD. We are eager to try it out!

WiTricity

Company Update

May 23, 2014

making wireless electricity a reality, faster

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