Embedded Software IP & Technology Transfer in Power Electronics Applications

Power supplies pushing matter at the speed of light

This blog is about FPGA in power electronics and a big part of power electronics is not motor control, but power supplies. On this topic, I recently had the chance to visit a very unusual power-electronics based power supply at CERN (European Organization for Nuclear Research) based in Geneva (Switzerland) while visiting a friend of mine, Davide Aguglia. This 120 MW power supply is meant to accelerate protons at 99.999% of speed the light in the largest particule accelerator of the world, called LHC (Large Hadron Collider). You can go on the CERN website for other interesting figures on the LHC.

Where are FPGAs in all this ? Well, obvisouly, in order to control the protons beam, the first step consists in quickly processing the huge amount of data coming out of the thousands high-precision transducers installed everywhere around the accelerator. Furthermore, these processing steps are essential to monitor and observe the protons collisions behavior in the experimental areas (ALICE, CMS, ATLAS & LHCb are all experiments at CERN for the understanding of matter of our universe; they are located along the LHC accelerator tunnel where collisions are performed). Xilinx have recently made an article on the subject in their Xcell magazine.

Then comes the control system used to accelerate protons. The actual load to be fed by power supplies is called a klystron – that is a large vacuum tube that produces radio frequency (RF) waves at high power, used for protons acceleration (by high frequency and high power electromagnetic waves). It can be rapidly thought that the challenge here is : how to precisely control this energy / high speed protons beam in terms of acceleration, speed and orbit precision ? There is an obvious challenge of control bandwidth to be achieved but most of it is to design power converter controllers to compensate every non-linearities and that this system is made up. High precision power converters are used to create strong magnetic fields (9 Teslas) to control the beam orbit (the beam is circulating in a circular path). An error in the magnetic field value leads to the lost of the right high-energy beam path with serious consequences. For this purpose power converters need a precision of the output current in the order of ppm (part per million), therefore high precision and high bandwidth control systems are required. On this topic, some researchers have presented interesting results comparing FPGA-based and DSP-based beam control.

Have you ever wondered how big is the source of protons ?

Myself and Davide Aguglia, scientist for CERN’s Power Converter Group (Accelerator & Beam dept.). Just behind us is the first part of CERN’s Linac2 particle accelerator put in operation in 1978.

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