V204 for special applications · Special version of V204-F with 3-fold output filter


 
The special version of the V204-F was developed for special applications requiring extremely limited electromagnetic compatibility interference (EMI). At full power at the output (22A and 120V) only 50mVpp could be measured.

This interference suppression was achieved by using an extra filter in addition to the LC output filter (which was already integrated). We also made use of filtered power supplies. All signal inputs and outputs are also fitted with lead-through filters developed specially for this purpose.

This device demonstrates that, with the corresponding experience, highly efficient PWM switching controllers can also be built completely free of interference.

NTT (New Technology Telescope)


The most modern telescope in La Silla (Chile) belongs to the ESO (European Southern Observatory) and is controlled via satellite from the ESO centre in Garching (near Munich). It is here that our V204-F PWM amplifiers control the azimuth and elevation axes.
When inclined, the 3.6-metre large mirror is kept in shape by a variety of actuators on the reverse side. The telescope is the first instance of this principle of active mirror optics in practice and serves as a prototype for the 4 large VLTs in Cerro Paranal in Atacama, which each use mirrors measuring 8 metres in diameter.


Demand for the best possible filtering technology:
Highly sensitive measuring instruments and light amplifiers do not allow electromagnetic (EMI) interference of any kind throughout the whole system. Therefore, one of the ESO specifications was for the development of a PWM controller with a high degree of efficiency. But it also had to provide the freedom from interference offered by linear amplifier, e.g. our DCP-2000/60.


To achieve the required filter quality, it was necessary to cascade various filters. More importantly however we had to position these in chambers which were electromagnetically isolated from each other.


These pwm power output stages provide an totally interference-free output voltage without electromagnetic emissions

Channel A with standard output stage filter, 3Vpp ripple at 5.6 Ohm load.
Channel B after special filter with <100mVpp ripple.
   
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