Archive for August, 2016

Feedback from the Camarillo Course Digital Control of Power Electronics

Tuesday, August 30th, 2016

Course survey feedback

We did a survey of what people thought of the course and here are a few  responses

“Had very high expectations of this course. Hamish delivered. Excellent for power engineers who are starting digital power. Thanks for putting this on…I only regret it is a 3 day course. I could sit here for 3 more days”

“This course was full of critical material not found in the app notes.  Very enjoyable and well taught.”

“Good course. Hamish knows his material. I’d like more examples, but I’ll be able to apply this coursework to my work.”

“Course provided extremely good overview of critical components and organization needed for digital control.  Definitely met my objectives from the course.  Thanks.  Suggestion to take some of the key components like linearization, precision extension and AA (anti-aliasing) filter and build labs around them would be a win.”

Plans for the course

We plan to add labs for the key components so that the learning is reinforced.

We do plan to keep the course technology vendor neutral and are working through how to do that.


Latching digital PWM – good feature or bad feature

Sunday, August 7th, 2016


This from a discussion in the Digital Power Electronics Control Group on Linkedin 

‘I was wondering if you could explain what you mean by “…ensuring that the PWM does not latch at the switching speed (very important for wide bandwidth)”. Isn’t the PWM comparator by nature a latch? Are you implying for best performance one should not use PWM shadow registers but rather do ” immediate” PWM updates?’

Latching digital PWM – good feature or bad feature?

Hamish from ELMG Digital Power

‘D. – I am not implying that latching is necessarily completely bad. Latching does have some uses as it provides another place in the system where you can reduce the effect of “aliasing in time” on transients. That said if you use a latching PWM then it is clear that you add delay. Whether this matters for your control depends on the bandwidth aim you have and whether you have designed a system that has low margin due to its power converter. But generally we always use our PWMs wide open with no latching delay to minimise the phase we get. We sample faster than the switching frequency and use the PWM as a down sampler. It means you need to take care of the “aliasing in time” elsewhere and be careful about intermod product magnitude from other non linearities in the loop – low pass filters are required along with a bit of modulation know how. Very doable and looks like magic when you need more bandwidth.’

Come join the discussion on all things Digital Power in the Digital Power Electronics Control Group

Latching digital PWM - good feature or bad feature

Look for the LinkedIn Group with this identifying z domain function.

Can I attend the digital power course remotely – Digital Power Electronics Control Training

Thursday, August 4th, 2016

Remote Attendance of the Digital Power Electronics Control Training Course

We got this question about the digital power electronics control training course

“Can I attend the Digital Control of Power Electronics Course remotely via the web or something like that?”

We do run webinars and they seem to be well received.

However we don’t know that the course would work remotely so the answer is no on attending remotely.

Come to the course instead.

Camarillo, California, August 22 through 24.

Camarillo, California January 30 February 2

Register here

California Course Digital Power Electronics Control Training

Dr Hamish Laird – Course Presenter




On the course do you address the issues that occur in digital control teams between software engineers and power electronics hardware engineers

Tuesday, August 2nd, 2016

How do hardware and software engineers talk to each other?

This is the extract from a recent conversation on LinkedIn between power electronics engineers of all different flavors.  It sums up beautifully the issues between hardware and software engineers in digital power electronics control developments. (Names shortened to protect the innocent.)

D. H.

‘Y. & A., I have no idea what half of the acronyms are which you (software) guys are using but, I get the feeling from A.  that optimized C (whatever that is) is slower for a multiplication than assembly. Y. seems to be saying that a particular version of C he likes creates a faster multiplication.
So, I’m just left confused. Which is it?
I’m from the 80’s. This is when a multiply was a simple, understandable add-shift, add-shift,….repeat 8 times and you’re done. Many modern processors have one command – MUL AxB. Nowadays, digital guys are telling me that this method is so complicated. Why? Why is a simple multiply so complicated now when 30 yrs ago it was routine and easy to understand?’

Hamish from ELMG Digital Power

‘D. H. – there is a really big disconnect between the software able guys like Y. and the non software able guys ( I am guessing you – sorry if I am wrong). It is often that sort of cultural mis-alignment that causes lots of issues in the development. We fix the cultural alignment for companies sometimes. And its a process and there isn’t really an easy road and, I hate to say it, some teams go under doing it. We created our digital training course as the result of a customer R and D manager asking us when we were in the middle of a fix up “How could we have avoided this?” ‘

D. H.

‘Hamish, You’re right about the cultural mismatch. (Yes, I’m not a software guy). My post a few days back concerned a software guy who had trouble communicating to me why his code was lengthy and complex, and I had trouble communicating with him as to why my view of a simple look-up table isn’t valid anymore. Maybe D. E. was correct, a “good” programmer should know how to deal with math.
Are these type of issues going to be addressed in your course?’


‘D. H. – In short yes. The slightly longer answer is. In the course we cover this culture issue both explicitly and implicitly. Team culture structure and organisation for digital power controllers are really important to success. And even more critical to sustained success when the “fix up” consultant has left the building. How we address this group culture issue in the course is by showing the attendees how to setup the conversation and documents so that the different types of people all can understand and contribute. Understanding and empathizing with the software engineers ethos, and what he values, is key to the power electronics converter engineer being able to do her job. And likewise. Engineers are technical people – which often speaks for itself in team dynamics. In the course we cover how matching the system partition to the team partition and to the system documents gives you a really good shot at success.’


‘D. H.  , It is a known problem where software get hard time from hardware and vice versa ,many project fell because of this issue
I solved this problem long time ago when I decided to learn software (computer science ) after a good career as a hardware designer and since then all the hardware and software issue solve internally :-)’

Hamish from ELMG Digital Power

‘Y. is right that you can just learn it all; hardware, software and control. The problem comes when you leave the job and the team have to do it without you. Super engineers are great until they leave the team. And not every company can employ one and most companies prefer a team to manage this risk.’

Come to the course in Camarillo, California,  August 22 through 24 and we’ll show you a good approach to dealing with this cultural mismatch.

Register here