HES-SO School of Engineering

HIL activities for the design of a Supercapacitors Charger

 

HES-SO School of Engineering

 

Challenge

The general context of this project is the feeding a X-Rays generator for medical applications (up to 50kW for few hundred milliseconds) directly from a supercapacitive tank. After one exposure, the tank is charged again to be re-configured, with no more than 1kW max power taken on a low voltage single phase grid (230/110V, 50/60Hz). As usual, supercapacitors are used as power buffers.
The HES-SO Valais-Wallis was elected by the company JOSEPH BETSCHART AG (www.xray-swiss.ch) specialized in developing and selling X-Rays generators. It was asked to develop in a reduced amount of time the supercapacitor charger mentioned above, having the main characteristics:

  • Input: 230/110V, 50/60Hz.
  • Max Charging Power: 1kW.
  • PFC, complying with all standard EMC requirements.
  • Reduced cost, as close as possible from industrialization.

The goal is to be able to conclude the developments associated with a new product that this company is about to propose very soon: http://www.xray-swiss.ch/produkte/genesis-dts/

Solution

Regarding the limited amount of time allowed for such a development, the following decisions have been taken to provide a solution:

  • Development and tests of the hardware to provide an operational system as fast as possible. The control implemented is a non-optimized control scheme, to be able to send to our partner a first version of the system as fast as possible. However, it can be used, tested and evaluated.
  • In parallel, use of HIL to identify, test and evaluate some new and optimized control schemes. When significant improvements have been made, files are provided to the partner allowing him to improve the behaviour if his product.

The main goal of such an approach is to allow us to continue to work on this product, without having it in the lab as most of the hardware developments are finished actually. For the industrial partner, it is the opportunity for providing some information and requests, and receiving back in a short delay some software improvements to upgrade his product. With the guarantee this will work as expected.

For the implementation of the system using a HIL600, the model is split on 3 of the 4 cores of the simulator. The time step for solving such a model is 500ns. One of the cores (that one which must compute the behaviour of the switching converter) is fully charged.
There is no special difficulty in such an implementation, using the standard and basic models provided by the main schematics library. Time spent for this first step, compiling, AOs and DIs configuration, was no more than 15-20 minutes.

The only specificity is that the switching frequency was set to 40 kHz (requirements from specifications). This could be considered quite fast for the HIL600. After analysis, results are anyway accurate and close to what was observed on the real hardware.

Conclusion

As a conclusion, and regarding the actual status of the project:

  • The hardware and its control, as developed at HES-SO, are today in use and tests by an industrial Partner.
  • The hardware and its control are still under study at HES-SO, except that the hardware is only a “virtual” one, implemented on a HIL600.
  • Study will continue: each new control strategy improved at HES-SO will be tested and validated on the HIL600. With positive results, files only will be forwarded to the industrial partner, with the guarantee that this will operate as expected on the real system.

 

Dr. Philippe Barrade

Professeur·e HES, responsable du groupe de recherche "Electronique de puissance et entraînements"

HES-SO Valais-Wallis, School of Engineering

Alain Germanier

Adjoint·e scientifique

HES-SO Valais-Wallis, School of Engineering

 
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