An Online On-State Voltage Measurement Circuit With Controlled Current Source for Thyristors

Thyristor is extensively utilized in High Voltage Direct Current (HVDC) transmission and other industrial fields, owing to its large capacity and mature technology. The reliability and safety of the system are directly impacted by the performance of thyristors, which is highly correlated with temperature. The junction temperature
$(T_{\mathrm{j}})$
of the thyristor can be calculated with the on-state voltage
$V_{\text{akon}}$
, a temperature-sensitive electrical parameter (TSEP). This paper proposes a technique for online measuring the
$V_{\text{akon}}$
, which can rapidly and accurately measure the
$V_{\text{akon}}$
without affecting normal operation. Accurately measuring the
$V_{\text{akon}}$
can be used to estimate the
$T_{\mathrm{j}}$
. The feasibility of the proposed technique is verified by
$T_{\mathrm{j}}$
calibration experiment and single-phase half-wave rectifier circuit. The accurate online measurement technology of
$V_{\text{akon}}$
has significant importance to ensure the safe and reliable operation of the thyristor and the whole system.