Archive for the ‘Control’ Category

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.  

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



Migration from MCU/DSP to FPGA for Power Electronics: Part 1 Software

Tuesday, November 17th, 2015

In a recent discussion we were asked about the migration path from MCU/DSP to FPGA.

“I am probably not alone when I use MCU/DSP devices to implement control algorithms, protection, logic etc to control the power hardware, using code such as ASM, C or C++, but want the advantages of FPGA. What suggestions do you have to start this migration, both in terms of a cheap evaluation board, and software tools, that can be targeted at driving various topologies and speeds.”

Thanks to Anthony W. for the question.  We get asked similar migration from MCU/DSP to FPGA for power electronics questions where the emphasis is more about retaining the value of an existing code base and coding team expertise while leveraging the flexibility of the FPGA.

As the first question states MCU/DSP devices are a common tool to implement control algorithms, protection, logic and sequencing for  control power hardware, using code such as ASM, C or C++.  However they do not have the power and flexibility of FPGAs. What is the best way to approach a migration from MCU/DSP to FPGA, both in terms of evaluation boards, and software tools, for a wide range of power electronic applications?

Best migration path MCU/DSP to FPGA for Power Electronics

There are a number of pathways to do this. The first one is High Level Synthesis. This is basically writing FPGA code in C. It is a very powerful tool but it does take some know how to make sure that you can get the most benefit out of the transition to FPGA. The downside of this is that it is quite expensive. There are however a couple of FPGA kits out there that do come with a kit-locked license (node-locked and locked to the FPGA model on the board).

Processor Inside

Another way is to use an FPGA with a processor, or processors, inside it. These processor can be soft-cores like Xilinx’s Microblaze or hard-cores like the twin ARM A9s in Xilinx’s Zynq series. (Reports on FPGA development projects show that almost 50% have some sort of processor.)  This processor allows you to directly port your code from your MCU/DSP to the Zynq/Microblaze and be ready to go. This may seem counter-productive as going from one processor to another without really gaining FPGA power is work for no reward.  The advantages come when you move parts of your code (the high intensity tasks such as the control algorithms) from C to the FPGA hardware. This provides a power boost for the important parts of your code whilst still having the simplicity of C for the easy flow of your code. A good analogy would be that the FPGA parts are the equivalent of the ASM parts on the MCU/DSP but with the superman type speed advantage of doing things in parallel in the FPGA fabric.

Best of both

Xilinx has also combined the HLS and the C coding options with their SDSoC product. It is designed for the Zynq SoC .  The coding is done in C. However you can use HLS to accelerate certain parts of the code for you to gain the most benefit.

Getting the most out of the Zynq solution does require either the expensive HLS toolchain and training in that or writing your own HDL. Another option is to purchase IP that other companies have written.  This allows you to create a fast and efficient system without needing to know coding of an FPGA in HDL or C.  ELMG Digital Power has a large suite of power electronics IP to get your application off the ground fast.

Prototyping and Development Platforms

In part 2 of this blog post, which is coming later, the answers to the questions

“How can I prototype this when the chip is BGA only?”

and

“What is an appropriate development platform or dev board?”

are covered.

Download the report ‘Your Digital Power Future – Roadblocks to Avoid’ to learn about the three key issues to watch out for in the Digital Control of Power electronics.


Download report now

Fixed Point Numerical Systems for Digital Control

Saturday, August 29th, 2015

One question which is commonly asked is “how do I represent fractional numbers on my fixed-point MCU, DSP or FPGA?” One of the best solutions to this is use of the Q number system.

The Q number system is a fixed point system where the available bits are divided amongst the integer bits (those to the left of the decimal point), fractional bits (those to the right of the decimal point) and a sign bit. You may ask “I know how integers are represented in binary but not fractions?” The answer is that just like integers, fractional bits are just multiplied by powers of two, except the powers are negative. For example:

  • 0.011B = 0*2-1+1*2-2+1*2-3 = 0.375

Q numbers can take on multiple forms with different numbers of fractional and integer bits. They are commonly written mQn or Qm.n where m is the number of integer bits and n is the number of fractional bits. Note m+n+1 = total number of bits available.

Arithmetic

Addition/Subtraction:

Q numbers of the same form can be added together with no issue. The only thing to consider here is overflow.

If you have different forms they need to be converted before the arithmetic. This can be done by shifting. For example:

  • 2Q13 << 1 is now 1Q14 (lose an integer bit and gain a fractional bit) and
  • 3Q12 >> 1 is now 4Q11 (lose an fractional bit and gain an integer bit)

Multiplication:

  • The rule when multiplying two Q numbers together is:
  • m1Qn1 * m2Qn2 = (m1+m2)Q(n1+n2)

Once the multiplication is complete, then a shift is needed to get it into the Q format the system needs.

The big issue with multiplication is overflow and precision loss. When there exists m > 0, then scaling back to your original system is difficult. For example:

  • 2Q13 * 2Q13 = 4Q26

In order to scale this back to the original 16 bits you either have to sacrifice integer bits (you have to be very careful that the top integer bits don’t contain information – limit the overflow) or lose precision by discarding fractional bits. The solution to this is to try and use systems where m=0.

Digital Control

Choosing the Q number system for digital control is important. The general rule of thumb is you want as much precision as possible and you want to avoid overflows in multiplication. Therefore the best solution is to make all your bits fractional (i.e. m=0). This gives as much precision as your system allows and makes sure there are no overflows (<1 x <1 = <1). In a 16-bit system this is 0Q15 (referred to as Q15).

Once you have your system then you need to make sure that all inputs and outputs fit this system and falls within the range -1 <= x < 1. This is as simple as setting your inputs and outputs to be +1 = full scale positive and -1 = full scale negative.

The key for this to work in a digital control system is to remember the gains on the inputs and outputs. This means remembering what +1 and -1 stand for. For example a voltage input may be -230V to +230V and an output maybe -400V to 400V. The input gain is therefore 1/230 and the output gain 400. Once you have these gains you need to include them in your design of the control system, whether it be through calculation or simulation. Failing to include them leads to incorrect margins and possibly instability.

One potential pitfall of the m=0 approach is how to deal with numbers greater than one. In digital control these can come up quite often generally in biquad filters. The trick is to this is to scale the coefficients by ½, perform the multiplies and then scale back by 2 (shift left 1). This does lose one bit of precision in this particular calculation however it is better than losing one fractional bit in all calculations.

Conclusion

Q number systems allow the designer to use a reliable fixed point system to represent fractional numbers. This allows the use of less expensive fixed point processors instead of the more complex and generally more expensive floating point alternatives.

Download the report ‘Your Digital Power Future – Roadblocks to Avoid’ to learn about the three key issues to watch out for in the Digital Control of Power electronics.


Download report now

Safety Critical Digital Control – Planes in Fog

Wednesday, December 24th, 2014

Safety critical digital control for airplanes in fog

This article was originally published in 2010.  It is part of the ELMG redux series of articles that will be republished over the summer.  These articles cover subjects in and around digital control of power electronics.

Redux – Safety Critical Digital Control – Planes in Fog

Just before Christmas 2006 I spent sometime (24 hours) in Copenhagen Airport as I waited for my plane after doing a week of meetings in Southern Sweden. I very nearly had a forced stopover in London at Heathrow as London fog shut that airport.  This stranded almost eighty thousand people who could not go on their holidays.

My connecting flight into Heathrow was cancelled due to that very fog in London. As a result I did not ever get to London and so I missed my connection out of London. Luckily for me I was re-routed the next day directly through Hong Kong missing the crowds of delayed passengers at Heathrow.  Thanks to all those that helped me.

Copenhagen Airport

As I waited at Copenhagen I thought about a number of things

  1. The large numbers of people at Heathrow and how their holidays would go? My sympathy to all the people who were delayed in Europe at or around Christmas time.
  2. Why, if an airliner can land itself at LAX in perfectly good weather, can an airliner not land itself in London in the fog? The pilot on my last flight to LA informed the passengers that the plane we were on would land itself at LAX. I cannot verify whether the plane did or did not land itself but we did get down safely.
  3.  What would my pre-school age daughter say if I did not get home for Christmas?

So if the plane can land on a sunny day in LAX why can it not land in the fog at London?

The guidance system on an airliner is an safety critical digital control system. It takes inputs from various guidance sensors (like GPS and inertial guidance) and produces outputs for the control surfaces like the elevators and ailerons. As such it will be a mixture of hardware and firmware  software. The program code is most probably written in a safety critical digital control useful language (not C) such as ADA. The method to write the software is (hopefully) well defined and the code is well inspected and walked through. The guidance system is then certified along with the aircraft by the FAA and other suitable safety authorities.

A Sunny Day in LA.

So let me say that again – on a good sunny day in LA my pilot can let the machine land itself but in London my plane cannot land because of the fog. I thought about why this was and even asked a friend. He said that it was “All because of the labour unions” which I hadn’t even considered. I decided that it may well be something else. Labour unions may have something to do with it but I don’t have time to write about that.

Critical Failure Modes Analysis

Consider the failure mode of the plane landing in Heathrow in the fog. If something goes wrong with the part of the guidance/landing system that takes care of height, then the airliner hits hard into the runway and makes a mess. Consider the same failure mode in the good weather at LAX. The plane is at the wrong height and would dive into the runway. Instead the over riding backup system looks out the window and takes control of the plane.

Safety Critical Digital Control on a plane needs a Pilot

So here is the skinny – it is OK for the plane to land itself so long as the backup override system is working. This backup is the pilot and so long as she isn’t struck down by food poisoning and she can see the runway she will not let the plane crash.

I am glad my flight to London was cancelled.

There have been incidents where the pilot has attempted to stop the plane crashing but the embedded systems in the plane have refused to help out. That, though, is something for another time.

Since this article was written safety of airliners and their safety critical digital control systems has come into sharp focus. Apologies and condolences to all and everyone who have been touched by the failings of digital control systems in the airline industry.   

Digital power electronics control processor choice – critical to success

Monday, December 8th, 2014

Digital power electronics control processor

The choice of control processor for your digital power converter is the most critical.  Which one should you choose from the multitude of available options?

A good lunch is all it takes

An engineer at our recent digital control course told me that the answer at his company was all about whether the FAE had taken you out for a good lunch.

He then went on to say that they had recently changed their digital power electronics control processor late in a development because this lunch approach to selection had not worked out so well.

What is important in a processor?

In a recent survey and discussion in the exclusive members only ELMG LinkedIn Digital Control Group  the most popular features and benefits of the digital power electronics control processor suggested were these. (not in any particular order of priority).

  • Price
  • Number of bits
  • ADC Precision
  • ADC sample and hold time
  • ADC aperture time
  • ADC delay
  • Tool chain flexibility and support
  • Emulation ability
  • Debug
  • Floating point
  • Fixed point
  • Device package
  • Processing power

Interrupts? PWM capability?

There was no mention of interrupt capability and no mention of PWM precision or PWM peripheral capability.  This may be because it is no longer the issue it was fifteen years ago.

Boundary scan and what we have always done

Surprisingly no one mentioned boundary scan for testing which we at ELMG find very useful.

Also surprising that the “we have used this processor forever and so will not change” was not mentioned in the Linkedin group discussion.

Will the purchasing department choose?

Before we get into technical details of processors it is useful to step back and remember that the supply chain for the chip needs to be secure.  Typically to a purchasing person this means that

  • The supplier is not going to go out of business.
  • The supplier has committed to not discontinuing the part.
  • The supplier’s balance sheet is not a large risk.
  • The supplier does not present a geographic or political risk.  If you are going to buy processors in large volumes natural disasters and revolutions can effect availability.
  • The supplier has good pricing.

If you are find yourself in the situation where there is no engineering choice of supplier best steps are to assess the proposed digital power electronics control processor against the “what is important” list above.

Some digital power electronics control processor options

There are a large number of processors that will do a good job.

A few stand out as having proved themselves useful over the years.

  • Microchip PIC and DSPic series
  • Luminary Stellaris Cortex M3
  • Ti  C2000 Series
  • Xilinx FPGA

Microchip

Microchip make great power control processors.  The processors and the peripherals around them are a really good choice of control processors for power electronics.  Typically purchasing departments love Microchip as a supplier.

Key strengths of the PIC and DSPic parts are the great support from Microchip and the microchip community. There are a large number of development kits that are available where the code, circuit and PCB layouts are all made available.  Examples of these include a 200W microinverter design and digital power starter kit.

Luminary Micro

Luminary microprocessors are ARM Cortex M3 parts.  The parts are excellent as they leverage the ARM eco-system of tools.  Initially we were reluctant to use these as the Luminary balance sheet was not as strong as it could be.  Then Texas Instruments (Ti) bought Luminary and integrated the products into the Ti range.  It is possible that Ti are not as committed as they were to the Luminary M3 parts.  Before you consider these parts make sure to ensure that the risk, or otherwise, of the processor being discontinued is clear.

Texas Instruments – C2000 series

Ti make very good digital power electronic controller processors.  The C2000 series provide a wide range of processors for power electronics.

Key features of these parts that make them most useful are

  • Very flexible three phase PWM
  • Good ADCs with synchronized sampling for three phases
  • Good code protection
  • Good tool chain

A part numbering example is TMS320F2812. The TMS320 is the family.  The F identifies the flash part and the 2812 is the model number.  The part is referred to as the twenty eight twelve.  This particular model is 32 bit with sixteen 12 bit ADCs and sixteen PWM channels.  This twenty eight twelve processor has been the workhorse for many motor drives and power supplies.  Other variants including the 2808 (twenty eight oh eight) are equally useful.

To extend the range upward Ti provide the Delfino range typified by the TMS320F28335 (twenty eight three three five). This is a floating point part.  The lower end of the range is covered by the Piccolo which is typified by the TMS320F28027. (Twenty eight oh two seven).

Why is it called the C2000 series?

The entire family of the C2000 series use the same code tools, and, if the code is structured well  it can be ported directly from one processor to the other.

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And it is called the C2000 series because the first parts available were ROM parts which had a C in the part number (C is short for ROM) instead of the F for Flash.

Product Support

Ti product support is good though it can be a little slow at times.  Pre-release silicon, labelled TMX, is often available from your local Ti supply chain.

The part data sheets are comprehensive and the discussion forums hosted by Ti are useful and often very productive.

Ti has a number of my favorite digital power electronic controller parts including the 2812 and the 28027.

Xilinx FPGA

The Xilinx FPGAs are not strictly designed as power electronics control processors.  They are Field Programmable Gate Arrays and so can do anything imaginable.  FPGA’s suit power electronics control very well.

Customised Peripherals

Often it is the peripherals in a power electronics processor that force the choice.  Typically a requirement for ADCs with a certain sample rate and a PWM that can make a certain waveform without excessive processor load force a certain choice.

If the MCU with the exact right combination of peripherals that you want does not exist then extra hardware is required.  Typically the selection process for an off the shelf processor part is always a compromise.

As an example, a peripheral set like

  • 4 UARTs,
  • 3 CAN Bus connections
  • 3 Ethernet along with
  • A five level three phase converter switching control with dead time compensation

can be implemented in a FPGA but a processor at reasonable price with this exact feature set is unlikely.

The beauty of the FPGA in this situation is that it’s peripheral set can be made totally customisable.  The design can be exactly as you need it.

Off the Shelf IP Core blocks

There are a number of off the shelf (OTS) IP Core blocks that can be used.  HDMI, SATA, VGA, Quad SPI, I2C, USB, high-speed serial, PCIe, UART, SPI, I2C, Ethernet and industrial ethernet like Ethercat  are all available off the shelf.  There are even open source solutions for some of these blocks.  These open source solutions come with very little support.  Commercial and proven blocks with support from vendors are usually better.

When building a power electronic controller the ELMG power electronics Control IP Core Blocks such as space vector modulators, phase locked loops and resonant controllers can be used along with off the shelf Ethernet stacks, USB connections and CAN bus controllers.  This gives a powerful custom digital power electronics control processor.

Extremely Complex Control – Too complex for the average engineer?

Complex control systems for power converters can be implemented using FPGAs.  This allows maximum flexibility and it allows the controller to be put into an ASIC for cost down when sales volume increases.

This complexity is a perceived risk for many teams when approaching FPGA.   However, since the FPGA is logic and a processor  is a connection of logic gates – why not put one inside the FPGA?  Then software engineers can use their existing expertise  with the added power of the FPGA.

Soft cores

This processor in an FPGA is implemented in a soft core.   A soft core, such as Xilinx’s Microblaze, is a micro built out of FPGA fabric.

The beauty of a soft core is that it can take any shape; small in size, really fast, an MPU or an MCU, with a multiplier or not. This allows you to size the softcore to your application.

Peripherals are then attached to the soft core. As an example, a custom three level PWM, 4 UARTs and 2 SPIs and you can then write C code for the soft core.

To take advantage of the FPGAs power add an ELMG Digital Power IP core block to accelerate the C code where it needs to be fast.  This allows you to use your existing C coding capability.

As an example, perform data transfer from an ADC using C, filter it fast and efficiently in FPGA fabric and then use the soft core with C to send it to a DAC or a custom PWM.

Best digital power electronics control processor?

The best digital power electronics control processor platform depends on the application.  Processors such as those from Microchip, Luminary and Texas Instruments are very good and are typically a good choice.  The ADC, processing and PWM performance determines which processors are suitable.  Additional communications and control peripherals then decide which processor part is best.

Click here to contact us for help in choosing processors.

Successful power converter developments and products use and have used the Microchip, Luminary and Ti parts.

FPGA based controllers for digital power provide power and flexibility that is a level above these standard digital power electronics control processors.  The ability to use soft core processors and FPGA  off the shelf IP along with the Digital Power IP Core Blocks makes the controllers more flexible and more useful.

The ELMG Digital Power IP Core Blocks are planned for release in March 2015.  See the list of proposed ELMG Digital Power IP Core Blocks blocks by clicking here

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