Section for Mathematical Physics
Abstract: The most frequently used ac/dc conversion is
performed at frequencies less than 1 MHz. However, a number of applications
require a much higher frequency conversion, up to 1 GHz, as e.g. in callibrating
oscilloscopes. At high frequencies voltages and currents are seldom measured
directly, instead measurement of power is performed in a Single Junction
Thermal Converter (SJTC).
The SJTC is placed in a coaxial wave guide which again is connected
to the a.c. system in which the voltage amplitude is to be measured. The
power dissipated in the thermal converter is proportional to the mean square
voltage. By comparing with the power dissipated for a d.c. current, the
mean square a.c. voltage is determined. The Danish Institute for Fundamental
Metrology (DFM) and Daniamet-Arepa vil develop a prototype high frequency
ac/dc converter for a.c. voltage measurements. The design is aided by mathematical
modelling of the converter performed at IMM and DFM. The modelling involves
numerical solution of the dynamics of an electric transmission line coupled
to an SJTC.
Collaborators:
Funding:
Erhvervsfremmestyrelsen: 180 KKr
Start date: July, 2000