Archive for July, 2016

Zynq Webinar Presentation Slides

Wednesday, July 27th, 2016

Dr. Tim King presented the Digital Power Control on a Zynq webinar.

In the presentation Dr. King detailed how the programmable logic fabric of the Zynq was fantastic for low latency and high precision digital power control.

zynq webinar presentation slides

What to do with the ARM A9 Cores?

He also outlined how to make use of the ARM A9 cores

The Zynq webinar presentation slides

The slides are available here


Download presentation




 

Three Day Digital Control Course August 22-24 California

Friday, July 22nd, 2016

The ELMG Digital Power Electronics Control Course

Three days of focused unique training in digital control of power electronics!

Our Digital Power Electronics Control Course overs the essential knowledge and know-how for engineers to implement digital power electronic control!

Come to the Three Day Digital Control Course in Camarillo, California August 22-24, 2016.  Register here.

How did the course came about?

Essentially the course came about because we were asked by one of our customer’s to provide one. The story is we were in the middle of a “fix up” job where the power supply had shown some control instability at its final release testing. The testing that showed the problem was passing a short circuit test of parallel connected power supplies. When the short circuit was removed the supplies came out of current limit, however they did not come out of the limit at exactly the same time. This created an oscillation where individual power supplies came out of current limit and then returned to current limit.  It was possible for the oscillation to continue indefinitely.  This was an unacceptable and embarrassing problem.

Six months of expertise in a three day course

During the six month project to rework the control code we spent lots of time teaching the team about the underlying issues that had been missed when the controller had been designed, coded and tested.  And part way through the “fix-up” the R and D manager suggested we could put a course together covering all that the team needed to know.

And so the digital control course was born

The first course covered exactly what we had discovered during the fix up job.  This included lots of digital expertise targeted for power electronics.  The areas we covered were diverse from;

  • Numeric precision loss in filters
  • Improvement of modulation spectral performance
  • Stability
  • The effect of numeric precision on stability
  • Best filter forms
  • Direct digital control design
  • Linearising control loops

What is covered in our course?

The course was created at the request of a Power Electronics Research  and Development manager.  He asked that we make it specific his team’s needs.  And this is why the course has the unique structure that it has.  We have been through the pain and heartbreak of having digital control development go wrong and have seen clearly where the repeated problems lie; our course addresses those areas.

Digital PWM and VPO modulators

One of the big differences between digital power electronics control and conventional analog control is the timer precision in digital modulators. This difference can be corrected or made negligible and in some cases can be made an advantage.  Spectral control in digital modulators is a focus area in the course as it is so effective.

Digital Precision in control blocks

It is possible to use a digital system and adjust the coefficients of the filters so that small inputs result in no output from the filter. Such scaling issues often lead to a loss of precision in the digital control system. The resulting slip-strike behavior can create limit cycle oscillations in the power converter output.

Direct Digital design of controllers

The “design then translation” approach of taking analog controllers to digital form can be avoided by using the direct digital design approach. This simple but powerful method of digital control loop design is covered in the course.

Converter non-linearity correction

Certain converter topologies are non-linear either in the control input to the output or the conversion ration.  Dealing with the converter non-linearity to achieve high bandwidth is key to stable parallel connected converters.

Stability

The course covers the fundamentals of stability from a physical basis with a focus on measurements of power converter transfers.  This along with a simple framework for managing margins and robustness is an integral part of the course.

Why we offer the course?

Understanding and implementing digital control of power electronics offers great advantages for configuration and flexibility. However, this is not without road blocks and issues that need to be designed around. This course provides the know how to get digital control working robustly and reliably.

How do I get on the course?

The course is next being run in Camarillo, California USA August 22-24.  To register for the course, click and visit the information page here. Press the ‘Register’ button on the page and this will take you to the shopping cart for the course. Complete the purchase to register for the course.

Next course

The next course is being held August 22-24 in Camarillo, California, USA.

Hotels

HOTELS

There are several hotels a short distance from the Ridley Engineering Design Center. The prices below reflect their current prices for August 2016. The last hotel listed is a nice beachfront resort if you do not mind the 25-minute commute to the office. Regardless of your selection, we recommend arriving on Sunday evening and departing Wednesday evening or Thursday.

 

Best Western Inn

295 E Daily Drive, Camarillo

0.3 mi.

805-987-4991

$100/night

Book.western.com

Residence Inn by Marriott

2912 Petit Street, Camarillo

2.8 mi.

805-388-7997

$185/night

Marriott.com

Courtyard by Marriott

4994 Verdugo Way, Camarillo

4.3 mi.

805-388-1020

$180/night

Marriott.com

Hampton Inn & Suites

50 W Daily Drive, Camarillo

1.1   mi.

805-389-9898

$175/night

Hilton.com

Hilton Garden Inn

200 Solar Dr., Oxnard

5.6 mi.

805-983-8600

$155/night

Hilton.com

Embassy Suites Mandalay Beach Resort

2101 Mandalay Beach Rd., Oxnard

15.4 mi.

805-984-2500

$200/night

Hilton.com

Travelling to the course

Transportation

Airports: There are three options for airports. Bob Hope Airport in Burbank will be the least congested and is serviced by American, United, Delta, Southwest and JetBlue:

Bob Hope Airport (BUR)

Los Angeles International Airport (LAX)

Santa Barbara Airport (SBA)

Shuttle: The Roadrunner Shuttle is a Camarillo-based service that provides door-to-door service from the airport. www.rrshuttle.com

Driving:

Bob Hope Burbank Airport (BUR) via US 101

https://goo.gl/maps/caMGB9QSEqP2

Los Angeles International Airport (LAX) via US 101

https://goo.gl/maps/kRBDQifyVfM2

Los Angeles International Airport (LAX) via Pacific Coast Highway (PCH)

https://goo.gl/maps/XPbBhNQYTzj

Santa Barbara Airport (SBA) via US 101

https://goo.gl/maps/2fGP3K7FMZx

About the presenter

3 Day Digital Control Course

Dr. Hamish Laird

Dr. Hamish Laird is a well regarded digital power electronics control engineer, researcher, lecturer and teacher.  Hamish is Chief Technology Officer at ELMG Digital Pwoer and holds a visiting academic position at the University of Canterbury in Christchurch, New Zealand.

During his career Dr Laird has worked on the control for;

  • High Voltage Direct Current Transmission
  • Reactive Power Compensators
  • AC and DC Motor Drives
  • DC to DC converters including LLC and phase shifted bridges
  • Medium and low voltage AC motor starters

Dr. Laird has worked for;

  • Alstom Grid (GEC Alsthom)
  • Eurotherm Drives
  • University of Canterbury
  • Aucom

Through ELMG Digital Power Dr. Laird  has provided advice, services and products to;

  • ABB
  • Enphase
  • Comsys
  • Evashred
  • TNEI
  • Eaton

Dr Laird says

“In designing and presenting the course we aim to have engineers able to use digital control in power electronics to achieve robust and reliable results.  See you in Camarillo”.

 

How to Register

Click here to register.  

P.S. Please note that the ELMG Digital Power course is being hosted at the Ridley Engineering Centre in Camarillo, California.  Ridley Engineering are processing all course registrations viatheir webstore.  Click here to register.  

APEC Presentation Slide Correction for b1 Coefficient

Wednesday, July 20th, 2016

At APEC this year we presented High Performance Digital Control of Power Electronics.  We then made the slides available and repeated the presentation as two webinars.

Click here to download the slides if you do not have them already  http://info.elmgdigitalpower.com/high-performance-digital-control-presentation

Thanks

Thanks to some good attention by a person who worked through the controller example,  we have noticed an error in one of the coefficients on the slide as shown below.

The correct value for the b1 coefficient is 0.00625.

Thanks to the helpful person who found this.

APEC Presentation slide correction for b1 coefficient

APEC Presentation slide correction for b1 coefficient

 

 

 

 

 

Inductor Go Round – Redux

Tuesday, July 19th, 2016

ELMG Redux from 2010

This post was originally published in 2010.  It is republished here because it looks like people are still doing the inductor-go-round.

So what is the inductor-go-round?  It is like a merry-go-round (carousel) except with inductors.  It can cost companies (or their startup backers) lots of time and money.  And usually when you are on the inductor-go-round it feels much like a carousel at a fair.  Round and round and sadly, not much progress.

Power Converters

Often the optimization of a power converter’s performance comes down to the optimization of the converter inductor. (It can also be optimization of the transformer but lets for the moment assume a non-isolated converter). For people with big and small inductors there is, it seems, an inductor go round.

What is a big inductor? At ELMG Electronics Design and Development we generally say that any inductor with mass more than 1 kg – and yes it says kilograms (1kg = 2.2 pounds) – is a big inductor. Some of you will say that until you have a 40kg inductor you don’t really have an inductor. Other inductors will be smaller.  I guess it is all a matter of what you are familiar with.

For the inductors for grid connected inverters people start with laminated iron or some other laminated material.  This is typically the  inexpensive choice.  Some others choose ferrite cores. Some start with another core material.

Air cored next

Then running first into core material problems they then move to air cored as the core is the cause of all the problems. They then either come up against either;

  • the magnetic field interference problem (the enclosure is now the core),
  • the fault rupture problems that occur with designing air cored mechanical restraints,
  • or the size constraint.

Powdered?

From here most people head to a modern core material such a powder core. These materials are not necessarily homogeneous and so they then realize that to get long life times requires careful consideration of the wear out mechanisms and to meet this requirement means using a quality core material vendor (See www.micrometals.com/thermalaging_index.html for a good first discussion on thermal aging). The lesson here is that not all core materials are the same.

Back again

At this point some people go back to iron or ferrite and others go to an alternative core material like an amorphous alloy. If they then cannot meet the price point then they may well go back to laminated iron.

At this stage the realization is that there is no magic answer. The optimization of power inductors becomes the requirement and there is usually a realization that the inductor vendors are not as able as they seem. In the defense of the inductor manufacturers it must be said that most power electronics companies struggle to correctly specify inductors.

Getting off the inductor go round means designing the inductor completely.

Free Webinar High Performance Digital Control on Zynq

Sunday, July 10th, 2016

If you have just sat down at your desk with a coffee, then put that aside for a minute and grab your diary.

Review your schedule for Tuesday 12th July 2016 and consider this stellar opportunity: on that day ELMG Digital Power will be hosting a FREE webinar on Digital Power using Xilinx Zynq SoC.

That’s right, from the comfort of your own desk you can join ELMG Digital Power (Members of the Xilinx Alliance Program) for their Zynq Digital Power Webinar and expand your knowledge and expertise by discovering:

* What is important in digital power, including numeric precision and latency
* How to design a compensator in the digital domain
* Why you would use a FPGA for digital power and why the Zynq SoC in particular
* Key issues in digital controllers in programmable logic, such as the serial-parallel trade-off, fixed or floating point,      choosing sample rates and what precision to use
* The building blocks for digital control and ELMG’s licensable IP cores
* IIR digital filter design (a case study) along with understanding the delta operator
* Using the ARM cores in the Zynq to your full advantage.

This webinar will be hosted and presented by Dr. Tim King, ELMG Digital Power’s Principal FPGA Engineer. Tim has considerable experience the design and implementation of varied digital control systems and IP for power electronics on FPGA platforms.

The webinar, which includes a short Q&A session, will be held on Tuesday 12th July and is available globally. Just choose a time that best suits you from these three options:

1. July 12th 2016 – commencing at 4pm in Christchurch NZ. (This will be 2pm Sydney, 1pm Tokyo, and 9:30am Delhi)





Register for Asia-Pacific




 

2. July 12th 2016 – commencing at 9am London (10am Berlin)





Register for Europe




 

3. July 12th 2016 – commencing at 1pm San Francisco (3pm Houston, 4pm New York)





Register for USA



Spaces are limited.  

See you at the webinar

 

 

Control Scope Integrated into Digital Power Controller

Friday, July 8th, 2016

How can I look at my digital signals in my power controller?

One of the big issues when working on digital control of power electronics is being able to look at the digital signals inside your controller.  In order to see what is going on inside the control the digital signals need to be brought out so you can look at them.

When a DAC isn’t good enough.

One way to do this is with a digital to analog converter (DAC) where the digital stream is sent out as an analogue signal.  These DAC channels are really useful and should be on every digital power electronics controller.  However processing power usually limits the logging or data streaming to a DAC to a low number of channels.  Each channel requires a scope channel of its own to do measurement.  Any measurement is limited in length to the scope’s memory and the scopes sample rate.

scope-capture

ELMG Digital Power ControlScope

Data Collection in the Controller and Detecting Events

There is also the issue that collecting enough data to allow event detection such as;

  • single sample errors
  • clipping
  • overflow
  • underflow or precision loss and
  • bursty instability due to precision loss

can be a very difficult large load on the control processor and memory if the data logging rate is very high or if the rate of the problem is very low.

Control Scope Integrated into Digital Power Controller

To solve this problem we put the data collection and logging into the controller but without loading the controller.

Using the Xlinx Zynq system on a chip (SoC) we use the flexibility of running Linux on one of the two ARM 9 cores to provide the high speed gigabit Ethernet connectivity.

Dlog Implementation

Dlog Implementation

We also use the Linux for secure remote access if required.

Using ELMG Power Core IP blocks and know how we create firmware in the FPGA fabric of the Zynq.  This connects to the Linux kernel and then the Linux user space.  Data can be logged at full sample rates into SD cards or MMX memory and simultaneously out via the Gigabit Ethernet to the internet.

To be very clear no Linux code is included in the power electronics control function which is all implemented in the FPGA fabric on the Zynq.

Put a scope on the other end of the Ethernet

The video shows the ELMG ControlScope application connected to the ELMG Digital Power Zynq data collection system (named Dlog).

This system implements a fully functional oscilloscope that allows the internal operation of the digital control to be shown and logged.

With gigabit Ethernet logging rates of 25 M bytes per second are possible using Dlog.

This means that logging of your power converter performance and waveforms, scope function or debugging can be done over the internet.

To evaluate the Dlog and the ControlScope than click below.  


Request Dlog and ControlScope Information