| 摘要 |
<p>A method and arrangement for determining the effective time of a voltage pulse of phase voltage generated by a frequency converter provided with an intermediate voltage circuit, the voltage pulses of the phase voltage being generated from the upper and lower voltage levels (U DC , 0) of the intermediate voltage circuit, the voltage levels showing a difference in potential (U DC ). The method comprises the steps of generating a first reference voltage (U ref1 ) and a second reference voltage (U ref2 ); scaling the phase output voltage by means of the scaling coefficient (k); comparing the low-pass filtered phase output voltage with the first reference voltage (U ref1 ); detecting a time instant (t 1 ) when the low-pass filtered phase output voltage exceeds the first reference voltage (U ref1 ); comparing the low-pass filtered phase output voltage with the second reference voltage (U ref2 ); detecting a time instant (t 2 ) when the low-pass filtered phase output voltage is lower than the second reference voltage (U ref2 ); and calculating the effective time of the voltage pulse on the basis of the time between the first and the second time instants and a constant term.</p> |
