Archive for the ‘Digital Issues’ Category

Inverter grid synchronisation – Six AC system frequency facts

Thursday, December 9th, 2021

With inverter grid synchronisation the key problem is that the grid frequency can vary.  In fact the frequency of AC systems around the world is different and is constantly changing.

  1. Aircraft AC systems run at 400Hz three phase.  They do this to make the motors lighter with less iron due to the volt second integral being lower.
  2. Some railway locomotive AC systems are 16.7Hz single phase.  These frequencies are chosen to minimise the current needed to charge the capacitance of the overhead line and so minimises the number of substations needed.  The 16.7Hz  is chosen to so as to not be a multiple of 50Hz.  The was made by rotary frequency changers (this is truly what they were called as power engineers often lack imagination) but is now also made by static power electronic frequency changers.  With modern static frequency changers with inverter grid synchronisation 16.7Hz is achieved.
  3. In Switzerland the railway has their own separate distribution grid.
  4. There have been railway frequencies as low as 8Hz and some train locomotives even operate from very low frequency AC with a frequency of zero.  DC is the AC you have when you are not having AC.
  5. Early on GE decided that 40Hz would be good for AC distribution but it did not catch on.
  6. There are aluminium smelters in Australia where they have or had 60Hz, 50Hz, 25Hz and 16 2/3 Hz AC systems and reportedly all at the same time.

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Other useful information for synchronisation.

  • NATO ships are 60 Hz,
  • The Swiss, German, and Austrian rail network reportedly changed to 16.7 Hz from 16 2/3 Hz  in 1995.  This to prevent over heating in rotary converters.
  • Japan has both 50 Hz and 60 Hz with the 50Hz built by the British and the 60Hz by the US after the second world war.  The two systems are linked by HVDC links.
  • 60 Hz is probably a better choice than 50Hz but it is too late now for the 50Hz countries.
  • Reportedly Tesla (not the car company) chose 50Hz first and then 60Hz.
  • There is a power station on the Argentina/Brazil border where half the generators make 60Hz for Brazil and half make 50 Hz for Argentina.
  • Sometimes, in some countries, on some days, 50Hz AC systems will run at 38Hz.  This presents an interesting inverter grid synchronisation problem.

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Grid frequency varies constantly as the mismatch between generator and load power changes.  In most countries the variation is not as large as the change to 38Hz.

Grid connected power converters must track or lock to the grid the grid.  The best way to do this is with a phase locked loop or a frequency locked loop.

Inverter Grid Synchronisation

Phase locked loops to track grid frequency are an essential part of grid connected converters. Click here to ask us about using an ELMG phase locked loop for inverter grid synchronisation.

May 18 Webinar – Basics of Digital Control of Power Electronics

Friday, May 14th, 2021

Our webinar series is back! Grab your lunch or a coffee and join us for this free webinar on the basics of digital control of power electronics.

From the comfort of your own desk you can join ELMG Digital Power for a free webinar to expand your knowledge and expertise about the advantages that digital electronics provides including:

* Flexibility
* Configurability
* Re-tuning the loop for component variation such as Electrolytic capacitor freeze out at low temperatures
* Management of the non-linearity of the converter
* Self-measurement of the loop response in closed and open-loop

and learn about the three key basics of digital control of power electronics these being

1. Limited number of bits.

2. Power converter characteristics including non-linearity

3. Limited PWM timer precision

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

The webinar on Basics of Digital Control of Power Electronics: Where to start and what is important will be held May 18, 2021, at 12 Noon PDT on Zoom.

Spaces are limited.  

See you at the webinar.

Click here to register

Free Webinar – Digital Control of Power Electronics using Zynq

Friday, January 31st, 2020

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 4th February and consider this stellar opportunity: on that day ELMG Digital Power will be hosting a FREE webinar on Digital Control of Power Electronics using Zynq.

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
* 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
* Building blocks for digital control with ELMG’s licensable IP cores
* Using the ARM cores in the Zynq to your full advantage.

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

The webinar on Digital Control of Power Electronics using Zynq, which includes a short Q&A session, will be held on Tuesday 4th Pacific Standard Time at 10am and is available globally.

Spaces are limited.  

See you at the webinar.

Click here to register

DIGITAL CONTROL OF POWER ELECTRONICS TRAINING – FOUR DAY WORKSHOP

Wednesday, April 25th, 2018

ELMG Digital Power invites you to register for our tailored training course, ‘Introduction to Advanced Digital Control of Power Electronics’

Register to secure your place.

Camarillo, California

The workshop is in Camarillo, California.

September 17th to 20th 2018

Be among the best digital power electronics control engineers and get the best digital control of power electronics training.

Register to secure your place.

Hands on Course – Digital Control of Power Electronics Training

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 digital 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.

DIGITAL CONTROL OF POWER ELECTRONICS TRAINING

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 to secure your place.

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.

DIGITAL CONTROL OF POWER ELECTRONICS TRAINING

Dr. Hamish Laird at the Camarillo Ridley Engineering Design Center

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.

These answers and more in the Linkedin discussion group.

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.

Introduction to Digital Control of Power Electronics

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.

Introduction to Digital Control of Pwoer Electronics - Four Day Training Workshop

Dr. Hamish Laird at the Camarillo Ridley Engineering Design Center