ELMG Digital Power are offering you the opportunity to attend our regular webinar on Digital Control in Power Electronics. This month’s webinar is titled “Frequency Responses for Control”.
This is an hour webinar covers
understanding frequency responses for control
how to use frequency responses for control in design of power converters
Thursday 12th October at 12 noon California time (3pm Eastern).
Webinar – Frequency Responses for Control.
Join ELMG Digital Power’s regular monthly Digital Power Webinar and expand your Digital Power knowledge and expertise.
The webinar will be hosted and presented by Dr. Hamish Laird. Hamish is ELMG Digital Power’s CTO and presenter and teacher of the Digital Control of Power Electronics Workshop. He has 25 years experience the design and implementation of varied digital control systems and IP for power electronics.
This exciting opportunity is free and includes a 15 minute Q&A session with Dr. Hamish.
Converter Frequency response from Analyzer Measurement
The webinar is scheduled for Thursday 12th October at 12 noon California time (3pm Eastern).
Click the link below to register. Spaces are limited.
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.
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:
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”.
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.
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.
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
On Tuesday 12thJuly, we would like to offer you the opportunity to learn about Digital Power using Xilinx Zynq SoC.
Join ELMG Digital Power (Members of the Xilinx Alliance Program) for their Free 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.
Xilinx Zynq SoC is a great processor for digital power electronics control.
Dr. Tim King presents
The free webinar on digital power using Zynq 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.
This exciting opportunity is free and includes a short Q&A session with Dr. Tim King.
Dr Tim King
When and where
The webinar will be held on 12th July and is available globally in your time zone. Just choose a time that best suits you from these three options:
Spaces are limited.
July 12th 2016 – commencing at 9am London, England. 1000 (10am) Berlin Germany.
July 12th 2016 – commencing at 1pm San Francisco, 3pm Houston, 4pm New York.
July 12th 2016 – commencing at 4pm in Christchurch New Zealand, 2pm Sydney Australia, 1pm Tokyo Japan, and 9:30am New Delhi, India
If you cannot attend at the scheduled time then register now and watch the recording later.
This year PCIM filled three of the Messe exhibition hall in the Nuremberg. There were a large number of exhibitors. This large turnout of exhibitors and the crowds attending shows that power electronics is going well in Europe and the world. The recent reasonable GDP growth in Europe suggests that the financial crisis of 2008 may finally no longer be a drag on the European economies.
Devices
Always at PCIM there are new and exciting devices launched. There is always lots of talk of how these devices will solve all the power loss and control problems. Better devices are always worth having and they add to the toolbox for power electronics engineers. Typically these new and improved switching devices allow higher power density by reducing losses and increasing the operating temperatures. As an end in themselves new devices are often a bit of a distraction. The fundamentals of the power converters job stay the same. Thermal design to keep the heat out, EM design to keep the noise in and control the converter to be stable and useful.
Gallium Nitride GaN
The GaN story is a good one. It is easy to be cynical about why GaN has appeared in the commercial market after being used extensively in military application for some time. The key issues that were clear in talking to GaN people was that the expected improvement from silicon is not as large as expected or as was initially indicated and that driving the devices is a challenge. As GaN devices are FET type devices with ON resistance they will be limited to lower voltages possibly up to 700VDC to 800VDC.
GaN is touted as the future for semiconductors. Solving the reliability issues may be the most pressing challenge to enable adoption.
Another issue with GaN devices is a perceived low reliability. This may resolve and my guess is it will as I remember when I first started working with IGBTs in 1990 they too were considered “unreliable.”
Silicon Carbide
Silicon carbide devices are well established and there are lots of switching devices and diodes available. These devices are being used to move the switching frequency up which is often assumed to be a good thing. The question that industry veteran Marty Brown so eloquently asks about this is “why go faster?” Time will tell whether faster switching gives the advantages that it should.
Silicon and stacks
Silicon devices are going from strength to strength. The effort being put into system design with gate drives and cooling is high. It is now possible to buy megawatt converters in cabinets ready for deployment into wind and solar applications. Vendors like Semikron, Danfoss and Infineon are leading the way with smaller vendors like Oztech and Agilestack either following quickly and at times leading.
It is still possible to use discrete devices. When talking with a vendor of an impressive graphite thermal interface material it was clear that they were surprised by the large numbers of TO247 packages being used in high volumes.
Capacitors
The trade off between required capacitor size and the switching frequency of three phase inverters is one of those design iteration choices that defines the physical size of the converter. If the switching is faster then there is less DC side capacitance needed but the switching losses are higher. And as we all switch faster is this optimization is starting to be limited by the inductance of the commutation loop. The available DC bus capacitors are very low inductance and the laminated DC bus bars are also extremely low inductance. There are opportunities to connect the capacitors directly onto the DC bus bars reducing the inductance to a very low value. SBE Capacitors have an excellent solution
Safety Critical Controllers – Functional Safety
The use of safety critical approaches in digital power control is recent. The automotive power electronic people have ISO 26262 requirements for how the gate drives and how the hardware need to behave in a fault. Medical device compliance requirements have long required risk management and safety critical partitioning of the system. Even household appliances have safety critical requirements in their product standards like IEC/EN 60335 and IEC/EN 60730. We have had 60730 code libraries for a number of processors for a while now and have IEC 61508 as the basis for our high reliability controllers. And the work that we do with controllers in equipment covered by the Machinery Safety Directive gives us a good insight into product risk management over the complete product lifecycle.
For a long while, and until recently, there has been little support for safety critical systems in power electronics. Partitioning of the controller is the way to meet the fault detection requirements of safety critical systems was a challenge. With the advent of ISO26262 in the auto industry there is now a demand for safety critical assessment and traceability inside the power converter controller. The use of safety critical techniques has long been useful in power converter control due to the inherent ability of bridge power converters to self-destruct.
There were microprocessors at PCIM which have (or will have) safety critical function as key to their function. These microprocessors have multiple cores that can implement either dual redundant systems or primary and secondary control to implement the safety critical control. This development is a great acknowledgement that there is need to treat power electronic systems as part of the safety critical development. Often times in the past the digital control in the power converter was not subjected to the same level of review and revision control. And often the digital control in the power converter can be updated in the field, leading to security issues for the digital power converter controller.
While micros with the partition and the safety critical features are a good step toward this there is probably still risk of hackers compromising the security of network connected safety critical systems. Engineering to avoid a Stuxnet type vulnerability in power converter controllers will be the challenge.
ELMG Control Platform for Safety Critical Systems
The ELMG Digital Power Control Platform allows safety critical partitioning of the FPGA function. The Xilinx isolated design flow ensures that each part of the the system can be separately verified and maintained. ELMG Digital Power experience in digital control for safety critical applications such as medical, household appliances and automotive traction allows safety critical analysis and design to appropriate process and performance standards.
Contact us to discuss your safety critical system.
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