Smart and flexible capacitor charger for warm environments

Detta är en Master-uppsats från KTH/Maskinkonstruktion (Inst.)

Författare: Tobias Rydberg; [2016]

Nyckelord: ;


A studio camera flash system being developed by Eascal AB needs a capacitor

charging power supply (CCPS) that can work in a hot environment without

problems and also not emit too much heat itself. The CCPS needs to be able to

operate from battery power as well as net power, so called off-line, and to

charge a capacitor to between 0-400 V.

Most power supplies do not act upon a rise in temperature until it overheats

and shuts down or goes into fail-safe mode where they stop delivering power.

The aim of this thesis is to investigate how a smart power supply which

features a micro-controller can change the behaviour of the unit or the user

so that heat emission is reduced if needed in order to avoid overheating. The

unit will be allowed to deliver less power in this mode.

Starting the project was the information gathering phase where a lot of

different kinds of power supply topologies were investigated and evaluated to

find the most suitable. A flyback converter was chosen for the battery driven

charger and a non-inverting buck-boost converter was chosen for off-line


Following the final choice of topology, simulations were made to ensure that

the power supply of choice would live up to the expectations and to specify

the ingoing components.

After the simulations were to satisfaction the prototypes were built to

verify the simulations, for testing and evaluating proposed techniques for

regulating the heat emission of the unit.

The sought after performance of the prototypes was never reached due to lack

of time and a need for better components that was not available. However the

simulations showed that the wanted performance was within reach and this was

verified by the worse performing prototypes living up to their simulated

counterparts. No actual physical work was done with the heat control, this

was conducted by theoretical reasoning and calculations. Results showed that

with a micro-controller the suggested chargers would be able to regulate

their heat emission by making changes to the charging profile or increase

dead-time between charge cycles.

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