## Author Archive

### Equivalent bits – a question from LinkedIn Group

Friday, March 10th, 2017

“I was looking through ELMG’s tutorial “Three Key Issues to Watch out for in the Digital Control of Power Electronics” (http://www.elmgdigitalpower.com/power-electronics-digital-control-free-report-on-three-key-issues/) and am having some trouble understanding the relationship between frequency, register size, and equivalent bits.

An example given in the “2. Timer Precision” section of the document reads:

‘Consider the case where the timer clock runs at 40MHz. If the variable period oscillator register has 256 bits then the maximum frequency that the VPO can make is 10MHz and the minimum is 39.0625kHz. The example LLC resonant power converter needs a variable frequency of 500kHz to 210kHz to perform the control. This means the VPO count register has a usable range from 80 to 191. This is 111 counts which is 6.8 equivalent bits or almost seven bits.”

Equivalent bits are a great way to look at numeric precision.

Come join the discussion to see how equivalent bits is calculated.  https://www.linkedin.com/groups/6677852/6677852-6242781250545942530

### A question about LCL filter

Wednesday, March 1st, 2017

#### I’ve got a situation where I have a generator hooked up to a rectifier doing space vector control. The rectifier has an LC filter. Inductor current and cap voltage is measured. The L from the generator makes up the second L. I didn’t put a virtual damper in the fpga code (like I should have) and am trying different things. This is only a prototype so just working is the main thing. Which would be the best way to go in my current situation?

*pole cancellation in the digital controller (in dq and 0 components)
*Adding a physical damping resistor to the filter cap
*increasing filter cap
*removing filter cap (voltage Pll seems to track fine on HIL and simulation but haven’t tried on power hardware)

Sorry about posting too much, but I’m thankful for any suggestions!

### What do you think the biggest issue is when diving into digital control?

Saturday, February 25th, 2017

## What do you think the biggest issue is when diving into digital control

This from D.P. -Lately to me it seems the biggest issue is maintaining a sustaining capability to the company where it is introduced. It requires at least one person that is decent at digital control design and then a team people that can implement. One person that can translate simulation to code, one person that can do state machines, one person that can do communications, etc. Lay on top of that maintenance and so on, it becomes a decent chunk of work.

Also digital technology changes so fast these days it can sometimes be difficult to keep up so you can take advantage of the advancements in processing capability and test capability. Many companies seem to fall behind because they don’t want to abandon their code base.

And this from J.F. – My take on this, as a former digital design engineer that now manages a power design group, is that it takes a very different mind-set to switch from analog power design to the SW/FW coding effort that it takes to implement the digital control algorithm. Since this discipline and way of thinking is foreign, it can be a major hurdle depending on the length of time the individual has been performing power design. Some of my folks are having an easier time to make this transition than others, but all are struggling to come up the learning curve.

### DIGITAL CONTROL OF POWER ELECTRONICS – A FOUR DAY TRAINING WORKSHOP

Monday, January 16th, 2017

ELMG Digital Power invites you to register for our tailored training course, ‘Introduction to the Digital Control of Power Electronics’ to be held in Camarillo, California on January 30th – February 2nd 2017.

ELMG Digital Power INC – Empowering you to achieve the Digital Control advantage

Register here

## Hands on Course

This hands-on course aims to provide engineers with solutions to the key issues in digital signal processing, using microcontrollers, microprocessors, DSP and FPGA. These solutions can then be employed effectively in the control of power electronics.

Over the four-day course, split into morning and afternoon sessions, participants will be provided with targeted training on digital power electronics control covering the detail of both digital control and power electronics and how they go together.  They will gain the ability to close a digital power converter feedback loop in a stable fashion by following repeatable easily understood steps, as well as techniques to understand what the effect digital control’s limited bandwidth, processing power, number of bits and dynamic range have in digital power electronic control.

## What you get from the course?

Engineers who attend the course will gain in-depth knowledge of the interaction of power electronics and digital control; this includes sampling and aliasing in the context of fixed and variable frequency switching power converters. There will be take away methods and steps to solve design issues such as one sample noise, precision limits in filters and controllers, non-linearity, quantization and other digital effects.  A copy of the slide slide presentation course booklet covering the material presented and lunch each day will be provided.

The 30 engineers who completed the Digital Control of Power Electronics Course August 2016

## Who is the course for?

The course has been specifically designed to meet the learning needs of engineers, regardless of whether you are:

• a practicing power electronics engineer,
• an experienced engineer moving into the area of digital control of power electronics,
• a software engineer working in digital power control teams,
• a firmware engineer involved in FPGA development in digital power control teams,
• a mid-career engineer transitioning from analogue control to digital control, or
• a recent graduate with some experience (<5 years) and looking to up skill in the area of digital control.

Register here

The course will be presented and led by Dr. Hamish Laird, Principal Engineer at ELMG Digital Power. An extremely well-regarded teacher, engineer, researcher and public speaker, Hamish works in developing digitally controlled power converters and controllers for converters. He is the author of seventeen academic papers on digital power electronics and power quality and has taught previous digital power courses at Camarillo.

Dr. Hamish Laird at the Camarillo Ridley Engineering Design Center

### Will there be a Digital Control of Power Electronics Course in Europe?

Sunday, November 20th, 2016

## Will the course be run in Europe?

At present there are no plans to run the course in Europe.  We suggest you attend the January 30 to February 2 Camarillo, California Course.

### Why was model based design not mentioned in the Zynq webinar

Friday, November 18th, 2016

Hello Mr. Laird—

My team at MathWorks works with our FPGA and SoC partners to promote use of MATLAB and Simulink. I didn’t have a chance to attend Dr. King’s webinar, but I scanned through his slides and was surprised to see no mention of Model-Based Design in these applications.

MATLAB and Simulink are used worldwide in both industry and academia in power electronics and, more specifically, motor control applications. Also, we have developed workflows and examples that target the Zynq-7000 SoC platform as well as the Altera Cyclone SoC platform.

–        Webinar with Avnet Electronics: How to Build Custom Motor Controllers for Zynq SoCs with MATLAB and Simulink

o   You may view the example used in the demo here

–        Webinar with Altera: Prototyping SoC-based Motor Controllers with MATLAB and Simulink

This use of MathWorks products has been widely covered in publications as well:

–        Xcell Journal: Motor Drives Migrate to Zynq SoC with Help from MATLAB

–        Xcell Software Journal: MATLAB and Simulink Aid HW-SW Co-design of Zynq SoCs (p.42)

–        Analog Dialog: FPGA-Based Systems Increase Motor-Control Performance

Given that your firm is promoting seminars, could we interest you in including information about MathWorks products in your seminars and webinars?

Please let me and my colleague Tony Lennon know how to follow up with you.

Sincerely,

–Eric Cigan

Hi Eric and Tony,

Thanks for the e-mail and thanks for the question about model based design.

I am sure that the Matlab products you refer to and the workflows associated are great and fit their purpose.  It is a shame that you did not attend the webinar as I am not sure you have taken the emphasis that was in the webinar.

So a little context about ELMG Digital power. We have Matlab licenses along with Simulink licenses. We use PLECs inside Simulink for power electronics simulation and use the PLECs Simulink and the HDL tools in the vivado tool chain to provide functional verification of FPGA applications that we build. We operate in market spaces where we have very high traceability and audit requirements.  We work on controller technology for power electronics principally in the larger converter space but also in the smaller safety critical market spaces.  Recently we provided the safety critical fibre optic communications links specifically designed for the modular IGBT converters for 26 Megawatt 6.6kV grid interactive UPS for the refinery industry.  We also work on HVDC transmission control, SVCs, large motor drives and other large static power converters.  Our specialty is in making the control suitable for the application and converter we are controlling.  We have deep domain knowledge in power converter characteristics and digital control of these converters.  We also create controllers for safety critical converter control including medical and safety systems for human protection.

The intent of the webinar was not to show how to design or implement controllers.  Rather the intent was to show how we have decided and then implemented our control platform.  We have created FPGA code IP blocks that perform a control function.  These code IP blocks are encrypted, tested, verified and exercised and are then available to the customer to purchase.  Verification is done with testbenches at an HDL code level.  Functional testing is done in simulation and then in real time simulation and then in power converter testing.  This is the product we provide to our customers.

Our webinar target audience includes some people who are not experienced digital control design engineers.  A significant portion of the people who consider our technology do not understand FPGA fabric and yet have safety critical requirements that require them to convince their regulators that the technology is appropriate.

We are Xilinx Alliance Program members so see and have all the reference material that you point to.  We recently were part of the presenting team in the Xilinx webinar Speedway series. We work carefully and closely with Xilinx and Avnet in how we promote the Xilinx family of products alongside our IP products.

Xilinx provide a large number of benefits to us through the Xilinx Alliance Program.  We have worked with Xilinx since 1997.  Avnet provide FAE support and global reach through their network – we have worked closely with Avnet on Xilinx work for seven years.

We’d be happy to include your material in our webinars on a partner basis.  Please let me know how your partnership program works, what we need to do to get the process of becoming a partner started and what the benefits are of the partnership program.

As you can see form the PS in the signature below we are running a training course in this very material in Camarillo January 30 to Feb 2.  Please register and come along.  Look forward to seeing you there if you can make it.